Patent Publication Number: US-8986229-B2

Title: Tongue strength evaluation system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Non-provisional application Ser. No. 13/479,640 filed May 24, 2012, U.S. Provisional Application 61/490,892 filed May 27, 2011, and U.S. Provisional Application 61/578,004 filed Dec. 20, 2011, which are each hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of biomechanics and more specifically to the evaluation of tongue movement and strength. 
     BACKGROUND 
     Measuring the movement and strength of an infant tongue during sucking on the nipple of a bottle or pacifier presents several challenges including, for example, the limited oral space of the infant available for direct measurement and alteration of motor control feedback mechanisms induced at the tongue interface, the limited amount of space available for instrumentation of the nipple, alterations required for instrumentation of the nipple which could affect natural feeding patterns, and obtaining accurate and precise measurements of tongue contact with the nipple interface. There are two stages of feeding where the tongue is applied to the nipple. During one stage, compression (squeezing) of the nipple by forces exerted on the nipple by the tongue compresses the nipple against the palate. In a nutritive sucking condition, a volume of fluid present in the nipple is pushed out of the nipple and into the oral cavity due to compression of the nipple. In the other stage, with the oral cavity sealed, the jaw and tongue drop down and away from the palate, enlarging the oral cavity and creating negative intra-oral suction. In a nutritive sucking condition, fluid is drawn (sucked) out of the nipple. Both stages are essential to infant feeding. 
     Adaptations to tongue muscle including decline of or lack of improvement in tongue strength may occur in premature infants who are artificially fed for a period of time. Using animal models, researchers have documented significant negative changes in tongue muscle responsiveness as a result of artificial feeding of newborn rats, which result in long term difficulties with feeding. As many as forty percent of premature infants exhibit both immature and atypical feeding patterns and those requiring prolonged respiratory support and those experiencing delayed oral feeding are most often affected. Because artificial feeding of premature infants may not be avoidable, determining whether tongue force is adequate for safe, efficient oral feeding, and developing interventions that lessen or eliminate any negative impact on the tongue muscle, such as interventions for strengthening the tongue during non-nutritive suck (NNS) and nutritive suck (NS), are necessary. Clinical use of NNS with preterm infants to promote oral feeding is well documented. Indications are that NNS intervention has a positive impact on transition from tube feedings to oral feedings, improves bottle feeding performance and decreases length of stay. Volume intake, number of tube feedings prior to reaching full oral feeds, and impact on growth and weight gain are outcomes that have not been positively associated with NNS, and the impact of NNS on other important oral feeding outcomes is not clear. Current measurement and evaluation methods are lacking and those that currently exist are subjective in nature and provide limited empirical evidence relative to assessment of infant feeding and swallowing. 
     SUMMARY 
     A system, method and apparatus to noninvasively evaluate the tongue movement and strength of a subject is provided. Measurements of tongue movement may be used to determine tongue strength parameters of an infant subject, including tongue force applied to a nipple during non-nutritive suck (NNS) and nutritive suck (NS). An intervention method directed at increasing NS tongue strength as well as NNS tongue strength of a subject with the intended outcome of positively impacting transition from tube feedings to oral feedings by improving bottle feeding performance of the subject is provided. The system, method and apparatus are configured to obtain direct measurement of the force of the tongue on the nipple interface in a noninvasive manner and to evaluate kinematic changes to the nipple during NNS and NS measurement by measuring tongue movement. The magnitude and direction of forces applied by the tongue to the nipple can be calculated through a calibration process of the evaluation apparatus and kinematic analysis of the applied forces such that measurements of tongue strength, work, impulse, and power or other derivations of force and time may be calculated from movement measurements obtained using the evaluation apparatus described herein. 
     An apparatus for evaluating the movement of the tongue of a subject is provided. Movement measurements obtained using the apparatus may be used to calculate tongue force and derive tongue strength parameters. The evaluation apparatus includes an insert configured to be positioned within a nipple element and to provide an output in response to deformation of the nipple element by a deformation force exerted on the nipple element during a sucking event. The output may be a resistive force exerted by the insert against the tongue of the subject during the sucking event, a movement measurement of the deformation force exerted on the nipple element during the sucking event, or a combination of these. The resistive force may be known or determined by calibration. The movement measurement output may be calibrated to the deformation or deformation force. The sucking event may be a nutritive sucking event wherein a fluid may be provided to the subject via the nipple element and the fluid may be in contact with the insert during the nutritive sucking event such that the nutritive sucking (NS) capability of the subject may be evaluated. The evaluation apparatus may be configured for non-nutritive sucking such that the non-nutritive sucking (NNS) capability of the subject may be evaluated. 
     The insert may be configured as a sensing device to provide an output which is a movement measurement of the deformation force exerted on the nipple element during the sucking event. The insert may be configured as a compliance element to provide an output which is a resistive force exerted in opposition to the deformation force and/or against the tongue of the subject during the sucking event. The insert may be configured to include a compliance element in communication with a sensing device, and may include an intermediate device in communication with one of the insert and the nipple element. 
     The evaluation apparatus may include a coupling device configured to be operatively connected to the nipple element, and to position the insert relative to the nipple element, and/or receive the movement measurement output provided by the insert. The coupling device may be configured to process the movement measurement by storing, displaying, analyzing and/or transmitting the output or a strength parameter determined from the movement measurement output. The coupling device may be configured to be sealably attached to a container to provide a sealed chamber in fluid communication with the nipple element. The sealed container may contain a liquid in fluid communication with the nipple element such that the insert is in contact with the liquid during the sucking event, and/or the sucking event may be a nutritive sucking event. 
     A system for evaluating the strength of the tongue of a subject during a sucking event is provided. The system includes the evaluation apparatus in selective communication with one or more devices configured as one or more of a data collector/analyzer, a transducer, a processor and a memory. The system may further include a calibration apparatus configured to calibrate the evaluation apparatus to provide a calibration of the output to the deformation of the nipple element. The evaluation apparatus may include a sealed chamber in fluid communication with the nipple element and a pressure gauge such that a change in pressure in the sealed container in response to deformation of the nipple element may be measured. 
     A method for evaluating the strength of the tongue of a subject is provided. The method includes providing an evaluation apparatus including an initial insert to a subject, conducting an initial sucking session with the subject using the evaluation apparatus including the initial insert characterized by a first resistive force, and evaluating the tongue strength of the subject using the output of the initial sucking session to determine if a strength objective or threshold established for the subject has been met. If the strength objection is not met, the method may further include providing the evaluation apparatus including a subsequent insert characterized by a subsequent resistive force which is different than the first resistive force, conducting a subsequent sucking session with the subject using the evaluation apparatus including the subsequent insert, and evaluating the tongue strength of the subject using the output of the subsequent sucking session to determine if a strength objective established for the subject has been met. The subsequent insert may be configured to exert a higher resistive force than the initial insert, to exercise the subject&#39;s tongue during the sucking event(s) to strengthen the tongue until the subject&#39;s sucking performance meets the threshold level or objective set for the subject. The method may include evaluation of the subject&#39;s nutritive and/or non-nutritive sucking capabilities. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic cross-sectional view of an instrumented nipple including an insert configured as a first example of a sensing device; 
         FIG. 1B  is a schematic bottom view of the instrumented nipple of  FIG. 1A ; 
         FIG. 1C  is a schematic side view of the instrumented nipple of  FIG. 1A ; 
         FIG. 1D  is a schematic bottom view of the instrumented nipple of  FIG. 1A  showing the sensor array of the sensing device of  FIGS. 1A-1C ; 
         FIG. 2A  is a schematic illustration of a tongue movement evaluation system including a cross-sectional view of a first example of a tongue movement evaluation apparatus; 
         FIG. 2B  is a schematic illustration of the tongue movement evaluation system including a second example of a tongue movement evaluation apparatus; 
         FIG. 3A  is a schematic illustration of a calibration apparatus for calibrating the tongue movement evaluation apparatus or an instrumented nipple; 
         FIG. 3B  is a schematic illustration of calibration data collected from the tongue movement evaluation apparatus of  FIG. 3A  using the calibration apparatus of  FIG. 3A ; 
         FIG. 4A  is schematic illustration of example data provided by the tongue movement evaluation apparatus of  FIG. 1D ; 
         FIG. 4B  is schematic illustration of example data provided by the tongue movement evaluation system of  FIG. 3A  using an evaluation apparatus configured for non-nutritive sucking (NNS); 
         FIG. 4C  is schematic illustration of example data provided by the tongue movement evaluation system of  FIG. 3A  using an evaluation apparatus configured for nutritive sucking (NS); 
         FIG. 5A  is a schematic cross-sectional view of a nipple element and shown in a sucking condition; 
         FIG. 5B  is a schematic cross-sectional view of an instrumented nipple including an integral compliance element and shown in a sucking condition; 
         FIG. 6A  is a schematic top view of a second example of an insert configured as a sensing device; 
         FIG. 6B  is a schematic cross-sectional illustration of an instrumented nipple including the sensing device of  FIG. 6A ; 
         FIG. 7A  is a schematic top view of an insert including the sensing device of  FIG. 6A  and a first example of a compliance insert; 
         FIG. 7B  is a schematic cross-sectional illustration of an instrumented nipple including the sensing device and compliance element of  FIG. 7A ; 
         FIG. 8A  is a schematic cross-sectional illustration of another example of an instrumented nipple including an insert, the insert including a compliance element and a sensing device and shown in a resting condition; 
         FIG. 8B  is a schematic cross-sectional illustration of the instrumented nipple of  FIG. 8A  shown in a sucking condition; 
         FIG. 9A  is a schematic cross-sectional illustration of another example of an instrumented nipple including an insert, the insert including a non-integral compliance element and an intermediate device and shown in a resting condition; 
         FIG. 9B  is a schematic cross-sectional illustration of the instrumented nipple of  FIG. 9A  shown in a sucking condition; 
         FIG. 10A  is a schematic cross-sectional illustration of another example of an instrumented nipple including an insert configured as a compliance and sensing insert and shown in a resting condition; 
         FIG. 10B  is a schematic cross-sectional illustration of the instrumented nipple of  FIG. 10A  shown in a sucking condition; 
         FIG. 10C  is a schematic cross-sectional illustration of the instrumented nipple of  FIG. 10A  shown in a resting condition with the compliance and sensing insert in a permanently deformed state; 
         FIG. 11A  is a schematic perspective illustration of another example of a compliance element; 
         FIG. 11B  is a schematic cross-sectional illustration of an instrumented nipple including the compliance element of  FIG. 11A ; 
         FIG. 11C  is an end view of the instrumented nipple of  FIG. 11B ; 
         FIG. 12A  is a schematic perspective illustration of another example of a compliance element; 
         FIG. 12B  is a schematic cross-sectional illustration of an instrumented nipple including the compliance element of  FIG. 12A ; 
         FIG. 13A  is a schematic illustration of a tongue movement evaluation apparatus including a coupling device; 
         FIG. 13B  is a schematic cross-sectional illustration of the tongue movement evaluation apparatus of  FIG. 13A  including the coupling device; 
         FIG. 13C  is a schematic exploded view of the tongue movement evaluation apparatus of  FIG. 13A  including the coupling device; and 
         FIG. 14  is a schematic flow diagram of a process for evaluating the tongue movement and/or tongue strength of a subject. 
     
    
    
     DETAILED DESCRIPTION 
     A system, method and apparatus for noninvasive evaluation of tongue movement and/or tongue strength, for example, infant tongue movement and strength during nutritive suck (NS) and non-nutritive suck (NNS), are provided. The system and method may include an intervention directed at training the tongue movement and increasing NS tongue strength and/or NNS tongue strength of a subject with the intended outcome of positively impacting a transition from tube feedings to oral feedings by improving bottle feeding performance of the subject. The system, method and apparatus are configured to enable noninvasive direct measurement of the force of the tongue on the nipple interface and kinematic changes to the nipple during non-nutritive suck and nutritive suck and movement measurement. Broadly, the system, method and apparatus comprise providing deformable materials which may be associated with sensors, allowing measurement of the movement of the tongue and degree of deformation of the deformable materials, the amount of force induced, etc., such as during application of force by the tongue during sucking. Without intending any limitation, the deformable materials may be configured as or associated with a nipple shape of known configuration, such as an infant bottle nipple, a pacifier nipple, a breast nipple shield, and the like. The sensor or sensors may be calibrated such that signals provided by the sensors over time may be collected and analyzed to identify stages of the feeding process and to determine the magnitude and direction of forces applied by the tongue to the nipple and kinematic analysis of the applied forces may be performed to derive the power, impulse, and work performed by the tongue, and other measurements of tongue strength which may be derived from the sensor signals. 
     As used herein, “nutritive suck” refers to the process of a subject (“subject”) feeding with a bottle or breast and receiving fluid. Therefore, a “nutritive suck” (“NS”) condition is one where the nipple element and/or the apparatus including the instrumented nipple is configured such that liquid is passed through the nipple during a sucking event. For example, the NS nipple may define an aperture through which liquid in communication with the nipple aperture, which may be liquid in a bottle or other container to which the NS nipple is attached, may flow through the nipple into a subject&#39;s oral cavity during a sucking or feeding event. In nutritive suck the fluid is typically a substance ingested by the infant during feeding, such as infant formula, water, milk, etc. As used herein, fluid type is not meant to be limiting. 
     As used herein, “non-nutritive suck” refers to the process of a subject (“subject”) performing the same task as nutritive feeding but not receiving fluid. A “non-nutritive suck” (“NNS”) condition is one where liquid is not flowed through the nipple, e.g., no feeding occurs. The nipple in NNS may contain an aperture for passage of fluid or may be sealed. In a non-limiting example, a NNS nipple may be configured without an aperture such that fluid flow through the nipple is prevented. In another example, a NNS nipple may be configured as a pacifier. In another example, an evaluation apparatus may include a nipple with an aperture which may be used in either of a NS (liquid provided) condition or NNS (no liquid provided) condition. 
     As used herein, an “instrumented nipple” is a nipple element including, attached to or in selective communication with an insert, where the insert may include one or more of a compliance element, a sensor, and an intermediate device. As used herein, “compliance” is a nipple or nipple element&#39;s tendency to resist deformation caused by applied forces, for example, the forces applied by the subject&#39;s tongue against the nipple during sucking, and a “compliance element” is an insert configured to modify the compliance of an instrumented nipple including the compliance element relative to a nipple element which is not instrumented. As used herein, “tongue strength” refers to a singular measure or plurality of measures used to assess the ability of the tongue to perform its function. Tongue strength measures include but are not limited to force, impulse, power and work. 
     Referring to the drawings wherein like reference numbers represent like components throughout the several figures, the elements shown in  FIGS. 1A-14  are not to scale or proportion. Accordingly, the particular dimensions and applications provided in the drawings presented herein are not to be considered limiting. 
     Referring to  FIG. 5A , shown is a schematic cross-sectional view of a nipple element generally indicated at  11 . The nipple element  11  is shown in a sucking condition, e.g., in a deformed condition caused by a deformation force exerted on the nipple  11 . The deformation force may be a tongue force FT exerted during sucking or feeding, or a calibration force FC exerted during a calibration process as described herein. The nipple element  11  is formed of a deformable material such as silicone, rubber, or other polymeric or natural material. 
     The nipple element  11  may be a standard nipple, e.g., a commercially available nipple configured as a pacifier or feeding nipple, also known as a bottle nipple. In another example, the nipple element  11  may be configured as a breast nipple shield which may be instrumented to provide an instrumented nipple  10  for use in evaluating tongue movement and/or strength in a NS configuration where the fluid source is a breast and the instrumented nipple  10  is placed in operative contact with the breast nipple. In a non-limiting example, the nipple element  11  may be configured for use with an infant. 
     The nipple element  11  may be configured as a non-infant (non-infant child or adult) pacifier and may be instrumented to provide an instrumented nipple  10  for use in evaluating the tongue movement, tongue strength and/or swallowing capabilities of a non-infant subject, for example, an elderly subject. In this example, the non-child nipple element  11  may be configured for either NS or NNS and adaptable to a fluid source or as otherwise described herein to enable evaluation of the subject&#39;s swallowing capability. It would be understood based on these examples that the configuration of the nipple  11  element shown in the figures is not intended to be limiting, and the nipple element  11  may be of a standard or commercially available configuration or a non-standard configuration. The nipple element  11  may be referred to herein as an unmodified nipple or as a non-instrumented nipple, in which case that the nipple element  11  refers to a standard nipple element, e.g., a nipple element, bottle nipple, breast nipple shield, etc. which has not been modified from its standard (commercially available) configuration or the nipple element  11  without instrumentation. A nipple element  11  may be combined with one or more inserts, as described in further detail herein, to provide an instrumented nipple  10 . 
     In a typical configuration, the nipple element  11  includes a tip portion  14  at one end and a flange portion  15  at the opposing end. The tip portion  14  is adjacent the intermediate portion  13  of the nipple, also referred to herein as the nipple body  13 . A base portion  12  is interposed between the body  13  and the flange portion  15 . The nipple element  11  shown in  FIGS. 1A and 5A  is configured as a non-nutritive suck (NNS) nipple, such that the interior surface  17  of the nipple wall  16  defines a nipple cavity  19  which is enclosed at the tip  14  and in communication with an opening  18  defined by the flange portion  15 . In a non-limiting example, the nipple element  11  may be configured as a pacifier and may include, as shown in  FIG. 13C  an extension  27  which may be provided as a handle for inserting, positioning and removing the nipple element  11  relative to a subject&#39;s oral cavity. The subject&#39;s oral cavity may also be referred to herein as the subject&#39;s mouth. 
     The nipple element  11  included in the instrumented nipple  10 A shown in  FIG. 1A  is shown in a first condition, which may also be referred to herein as a resting or non-deformed condition. In the resting condition, minimal to no forces are exerted by the tongue on the nipple element  11  such that deformation of the nipple element  11  is minimal to none. A nipple element  11  is shown in  FIG. 5A  in a second condition, which may also be referred to herein as a sucking or deformed condition. In the sucking condition, the nipple is positioned in the subject&#39;s mouth such that a first portion  20  of the nipple element  11  is in contact with the subject&#39;s palate (not shown), and a constraining force FP is exerted by the palate against the first portion  20 , which may be referred to herein as the palate facing portion of the nipple. During sucking, the subject&#39;s tongue (not shown) exerts a tongue force FT on a second portion  21  of the nipple element  11 , shown in  FIG. 1A  as FTx and in  FIG. 5A  as FT1. The second portion  21  may be referred to herein as the tongue facing portion  21  of the nipple element  11  and generally opposes the palate facing portion  20  when the nipple is positioned in the subject&#39;s mouth. In a sucking condition, as shown in  FIG. 5A , the tongue force FT compresses the nipple element  11  by deforming wall  16  of the tongue facing portion  21  toward the palate facing portion  20 . The magnitude of the deformation, which may be measured by a deformation distance D, is shown as D1 for the sucking condition shown in  FIG. 5A . It would be understood that the deformation distance D of the nipple in the resting condition shown in  FIG. 1A  is zero. 
     The nipple element  11  exerts a resistive force FR in opposition to the tongue force FT. The resistive force FR is a function of the compliance of the nipple element  11 , e.g., the nipple&#39;s tendency to resist deformation caused by applied forces such as the tongue force FT. The compliance of the nipple element  11  and the resistive force FR may be determined by one of more factors, including but not limited to the material characteristics of the nipple element  11 , including the material type, elasticity, hardness, etc., and the wall thickness W of the wall  16 . As shown in  FIGS. 5B through 12B , the effective compliance of the nipple element  11  and the resistive force FR may be modified by changing the configuration of the wall  16  in the tongue facing portion  21  and/or adding a compliance element configured to exert a resistive force FR in opposition to a tongue force FT to provide an instrumented nipple  10 B. As described in further detail herein, instrumented nipples  10  of varying compliance and resistive force FR may be used in an intervention method as shown in  FIG. 14  to develop tongue strength in a user subject such as an infant, which may be a preterm infant. 
     Deformation forces exerted on a nipple in a sucking condition can be evaluated by instrumentation of the nipple element  11  using an insert including or configured as a sensing device, such as but not limited to a sensing device  30  described in further detail herein and illustrated by the figures, to provide an instrumented nipple  10 . The compliance and/or resistive force of a nipple may be modified by instrumentation of the nipple element  11  using an insert including or configured as a compliance element having a known compliance and resistive force FR, such as but not limited to a compliance element  80  described in further detail herein and illustrated by the figures, to provide an instrumented nipple  10 . The known compliance and/or resistive force FR may be determined by configuration of the instrumented nipple  10 , or by calibration of the instrumented nipple  10  using a calibration apparatus  60  as provided herein. The term “instrumented nipple,” as used herein, refers to a nipple including or in operative communication with at least one insert, where the insert may be a sensing device  30 , a compliance element  80 , an intermediate device  37 , a combination of two or more of these, or a nipple which is otherwise configured to include an insert configured to directly measure the deformation force exerted on the nipple and/or to provide a nipple characterized by a known compliance or calibrated resistive force FR. 
     In a first non-limiting example,  FIGS. 1A through 1D  show an instrumented nipple  10 A including a nipple element  11  and an insert configured as a sensing device  30 A. The sensing device  30 A includes a sensor array  31  consisting of a plurality of sensors  32 . In the non-limiting example shown, each sensor  32  includes a piezoelectric crystal. Each of the piezoelectric sensors  32  is positioned in communication with the wall  16  of the nipple element  11 . Each piezoelectric sensor  32  may be positioned, for example, by adhering, bonding, embedding, submerging, bracing, fixturing using a mechanical fixture or support device or otherwise affixing or positioning the piezoelectric sensor  32  to the inner wall surface  17  or within the wall  16  in a specified location. For example and as shown in  FIGS. 1A-1D , the plurality of sensors  32  may include groups of sensors  32   a ,  32   b ,  32   c . The first group of sensors  32  may include one or more piezoelectric sensors  32   a   1  . . .  32   an  arranged in the base portion  12  of the nipple element  11 , where little to no movement of the nipple element  11  occurs during sucking. The second group of one or more piezoelectric sensors  32   b  may include one or more piezoelectric sensors  32   b   1  . . .  32   bn  arranged in the body portion  13  of the nipple element  11 , where substantial movement of the nipple element  11  occurs during sucking, as shown in  FIG. 2B , which shows the instrumented nipple  10 A in a sucking condition. The third group of one or more piezoelectric sensors  32   c   1  . . .  32   cn  may be arranged in the tip portion  14  of the nipple element  11 . The first, second and third groups of piezoelectric sensors  32 A,  32 B,  32 C form the sensor array  31  shown in  FIGS. 1C and 1D  in a resting condition. Each of the piezoelectric sensors  32   n  is identifiable to a set of coordinates X, Y, Z describing the position of the respective piezoelectric sensor  32  in the array  31 . For example and referring to  FIGS. 1C and 1D , the sensor  32   a   3  is identifiable to coordinates X1, Y1, Z1 in the array  31 . Likewise, sensor  32   b   4  is identifiable to coordinates X2, Y2, Z2, sensor  32   b   2  is identifiable to coordinates X3, Y3, Z3, and so on. (Note, Z2 and Z3 are not shown in  FIG. 1C  for clarity) It is understood that the values of X, Y, and Z will change as the position of the corresponding crystal sensor  32   n  changes during deformation of the instrumented nipple  10 A. The number, grouping, location, arrangement, means of attachment and/or positioning of piezoelectric sensors  32  in the array  31  is intended to be non-limiting, and other arrangements of a plurality of sensors  32  and/or configurations of the array  31  may be used in collecting sucking deformation data from an instrumented nipple  10 A. 
     Each of the piezoelectric sensors  32  may be operatively connected to a lead  33 , which may be, for example, a conductive wire configured to conduct electrical signals from each sensor  32  to a data collector/analyzer  59  (see  FIG. 2A ) which may, in the present example, be configured as sonomicrometry instrumentation for use in performing kinematic analysis of the signals received from each sensor  32  over time during a feeding or sucking event. The leads  33  may be connected directly to the data collector/analyzer  59 , or may be operatively connected to a communications interface  35  configured to transmit the signals from sensors  32  to the data collector/analyzer  59 . The communications interface  35  may be, by way of non-limiting example, a connector receiving the plurality of leads  33  and connectable to the data collector/analyzer  59  or a portable data storage device (not shown) such as a SIM card, flash drive, etc. which may include RAM or flash memory and be used to transfer the collected data to the data collector/analyzer  59 . The plurality of leads  33  may be routed through a conduit  34 , for ease of handling and/or to protect the leads from damage, etc., as shown in  FIGS. 1B and 2B . In another example shown in  FIG. 2B , the sensors  32  or communications interface  35  may be configured for wireless transmission of the sensor signals  32  to the data collector/analyzer  59  using any suitable means of wireless transmission such as Bluetooth®, RFID, Wi-Fi, ZigBee® or other wireless methods. Further, the data signals can be processed, displayed, transferred to a processor for additional analysis, stored in memory, etc. 
     A substance  24  is provided to the nipple cavity  19  such that the plurality of piezoelectric crystal sensors  32  are submerged or otherwise inter-operatively connected through the substance  24  to allow sound waves to travel between the submerged piezoelectric crystal sensors  32 . The substance  24  may be, by way of non-limiting example, a saline solution, liquid, gas, deformable solid or a combination of these which is capable of transmitting sound waves between the piezoelectric crystal sensors  32  collectively contained by the substance  24 . In one example, the piezoelectric crystal sensors  32  may be embedded in the wall  16  such that the substance  24  is the material from which the nipple is made, e.g., the wall material, and sound waves are transmitted between the embedded crystal sensors  32  through the material of the nipple wall  16 . The instrumented nipple  10 A may be configured as a NNS nipple, as shown in  FIGS. 1A and 2A , or as a NS nipple as shown in  FIGS. 1C and 2B . In the latter example, the instrumented nipple  10 A configured as a NS nipple may include an aperture  25  at the tip end of the nipple element  11 , such that the substance  24  may flow through the nipple element  11 , into the subject&#39;s oral cavity during a feeding or sucking event. In this example, the substance  24  may be a nutritive substance such as a water, formula or milk based substance, provided to the nipple cavity  19  in sufficient volume during a feeding or sucking event to continuously submerge the plurality of sensors  32  during an evaluation sequence, as shown in and described for  FIG. 2B . 
     Referring again to  FIG. 1A , the instrumented nipple  10 A may be configured as a NNS nipple, wherein the instrumented nipple  10 A includes a non-permeable membrane  22  operatively and sealably connected to nipple element  11  to enclose the opening  18 , thereby containing the substance  24  in the nipple cavity  19  and forming a first sealed chamber  23 . The non-permeable membrane  22  may be flexible, such that pressure changes within the first sealed chamber  23  may be transmitted through the membrane  22 . As shown in  FIG. 2A , the plurality of leads  33  may be extended from the plurality of sensors  32  in the sealed chamber  23  through the nipple wall  16  or membrane  22  in a sealed manner to the data analyzer/collector  59 , which may be via the communications interface  35 . In a non-limiting example, the instrumented nipple  10 A configured as shown in  FIGS. 1A and 1B  may be used as a pacifier-type evaluation apparatus  100 A to collect data during an evaluation sequence, during which the instrumented nipple  10 A is provided to a subject for collection of data during sucking. In other non-limiting examples, the NNS instrumented nipple  10 A shown in  FIG. 1A  may be included in the NNS evaluation apparatus  100 B shown in  FIG. 2A , and the NS instrumented nipple  10 A shown in  FIG. 1C  may be included in the NS evaluation apparatus  100 C shown in  FIG. 2B . The data may be collected over a period of time and may include data representing a plurality of sucking cycles. 
     Deformation of the instrumented nipple  10 A by the subject&#39;s tongue during the evaluation sequence will cause deformation of the sealed chamber  23  resulting in a change in kinematics of the plurality of piezoelectric sensors  32  and deformation of the sensor array  31 , as illustrated in  FIG. 2B . Sound waves transmitted and received between the sensors  32  in the array  31  during the deformation and evaluation sequence are output in real time as electrical signals and measured using the sonomicrometry instrumentation included in the data collector/analyzer  59 . Knowing the speed at which sound waves travel within the connecting substance  24  between the respective crystal sensors  32  of the array  31  allows calculation of the instantaneous distances between all the crystal sensors  32  in real time using the established technology of sonomicrometry. Using triangulation or trilateralization, the three-dimensional kinematics of the crystal sensors  32  can be determined, including the positional coordinates X, Y, Z of each crystal sensor  32   n  in the array  31  at each measured point in time. 
     Alteration to the kinematics of the crystal sensors  32  is a direct result of forces FT applied by the tongue against the instrumented nipple  10 A as the instrumented nipple  10 A is constrained against the palate of the subject&#39;s mouth by a palate force FP. By placing the crystal sensors  32  in a known array  31 , signal data collected from the crystal sensors  32  may be used to determine the direction at which force is applied to the instrumented nipple  10 A using basic physics principles. Inverse dynamics can further interpret force vector components FTx, FTy, FTz (not shown for clarity) of the tongue force FT and be clinically interpreted to the muscles of the tongue. 
     When the properties of the nipple materials and sound conducting substance  24  are known, for example, through testing properties such as mass, compliance and viscosity, the forces exerted on the nipple  10 A during deformation can be derived using the acceleration of the crystal sensors  32  independent of a sensor signal calibrated to the deformation of the instrumented nipple  10 A. 
     Referring to  FIGS. 2A-4C , an instrumented tongue strength evaluation apparatus  100  (“evaluation apparatus”) may be calibrated using a calibration apparatus, such as the calibration apparatus  60  shown in  FIG. 3A  to calculate the magnitude of force applied to the instrumented nipple  10  in relation to the deformation of the nipple  10 . Forces applied by the tongue during evaluation of a subject correspond to the following equation:
 
 FT∝DT≅FC∝DC∝ Nipple Compliance  (1)
 
where FT are the forces produced by the tongue on an instrumented nipple  10 , DT are the distances the nipple deforms due to the tongue, such as D1 shown in  FIG. 5A , FC are the forces applied to the instrumented nipple  10  during a calibration procedure to deform the instrumented nipple  10 , where the distances the nipple deforms due to the calibration force are DC, as shown in  FIG. 3A . Measurement of changes in pressure within the sealed chamber  23 , obtained, for example, from the evaluation system  105  and evaluation apparatus  100 A shown in  FIG. 2A  using the calibration apparatus  60  shown in  FIG. 3A , may be used in conjunction with or independent of the kinematics of the crystal sensor array  31  to calibrate the instrumented nipple  10 A. It would be understood that calibration does not need to be performed for every nipple or at every instance of use, for example, when the properties of the nipple are known or established.
 
     Referring now to  FIG. 2A , shown is a tongue movement evaluation system generally indicated at  105 . The evaluation system  105  includes a sensor data collector/analyzer  59  and a pressure gauge  57  in communication with a processor  58  and a tongue movement evaluation apparatus  100 B, using wired or wireless communication methods. The collector/analyzer  59  in the present example may be configured as a sonomicrometer or include sonomicrometry instrumentation for analyzing data collected from the plurality of piezoelectric crystal sensors  32  included in the instrumented nipple  10 A of the apparatus  100 B. Each of the gauge  57 , processor  58  and collector/analyzer  59  may include or be in operative communication with memory, which may be configured as one or more of Read Only Memory (ROM), Random Access Memory (RAM), electrically-erasable programmable read only memory (EEPROM), etc., of a size and speed sufficient for executing the functions performed by the respective gauge  57 , processor  58  and collector/analyzer  59 . Each of the gauge  57 , processor  58  and collector/analyzer  59  may include a user interface, which may include a display and/or input/output interface for communicating data, analysis results, messages, etc. The configuration shown in  FIG. 2A  is not intended to be limiting, and it would be understood that functions performed by each of the elements  57 ,  58 ,  59  may be performed by another of the elements  57 ,  58 ,  59  as configured to do so. For example, the sensor data collector/analyzer  59  may be configured to also perform functions of the processor  58 . 
     The evaluation apparatus  100 B, in a non-limiting example, is configured for non-nutritive suck (NNS) and includes the instrumented nipple  10 A including the sensing device  30 A and configured as shown in  FIG. 1A , where a sensor array  31  is submerged in the conducting substance  24  contained in a first sealed chamber  23  formed by the nipple cavity  19  and enclosed by the membrane  22  (see  FIG. 1A ). The instrumented nipple  10 A is sealably connected to a container  40 , which in the non-limiting example shown may be configured as an infant feeding bottle, commonly referred to as a baby bottle. The bottle  40  includes a bottle cavity  41  defined by the inner surface  45  of the bottle wall  44 . Sealing contact may be provided by retaining the flange portion  15  of the instrumented nipple  10 A against the bottle opening  43  using a collar  28  selectively connected to the end portion  42  of the bottle  40 . The collar  28  may be, in the example shown, a standard bottle collar used with an infant feeding bottle or a ring-shaped retainer threadable onto the end portion  42  to retain the instrumented nipple  10 A in sealing contact with the bottle  40 . As shown in  FIG. 2A , a second sealed chamber  46  is defined by the bottle cavity  41  enclosed by the instrumented nipple  10 A, such that the first sealed chamber  23  and the second sealed chamber  46  are separated by the membrane  22 , e.g., the membrane  22  is in operative communication with both the first and second sealed chambers  23 ,  46 . The membrane  22  may be configured as a flexible non-permeable membrane such that changes in pressure in the first sealed chamber  23 , such as pressure changes occurring during nipple deformation, may be transmitted through the membrane  22  to proportionally change the pressure in the second sealed chamber  46 . 
     An intermediary tube  54  may be in fluid communication with the second sealed chamber  46  at a first tube end  55 , and in fluid communication with the pressure gauge  57  at a second tube end  56 , such that changes in pressure in the second sealed chamber  46  may be measured and collected by the pressure gauge  57 . The pressure gauge  57  may include an analog/digital (A/D) transducer (not shown) for conversion of the pressure signal to an electronic signal, such that pressure measurements may be transmitted to and/or collected by the processor  58 , stored as data, etc. The bottle  40  may include an adapter  53  configured to receive the first tube end  55  and position the intermediary tube  54  in fluid communication with the second sealed cavity  46 . 
     Deformation of the instrumented nipple  10 A will result in a deformation of the first sealed chamber  23  resulting in a change in pressure in the first sealed chamber  23  and movement of the flexible membrane  22 , which results in a corresponding change in pressure in the second sealed chamber  46 . The corresponding change in pressure in the second sealed chamber  46  may be recorded. The pressure data may be collected by the pressure gauge  57  and used in conjunction with the kinematics data collected from the sensor array  31  and provided by the sonomicrometry instrumentation of the sensor data collector/analyzer  59  to evaluate the deformation force (magnitude and direction) being applied to a calibrated instrumented nipple  10 A. The NNS evaluation apparatus  100 B and instrumented nipple  10 A may be calibrated as shown in and described for  FIGS. 3A and 3B . 
     Referring now to  FIG. 2B , shown is the tongue movement evaluation system  105  as described for  FIG. 2A , shown in use with a tongue movement evaluation apparatus  100 C. The evaluation apparatus  100 C, in a non-limiting example, is configured for nutritive suck (NS) and includes the instrumented nipple  10 A including the sensing device  30 A and shown in a sucking condition in  FIG. 2B . The NS instrumented nipple  10 A is configured as shown in  FIG. 1A , where the nipple tip portion  14  defines an aperture  25  configured to allow flow through of the substance  24  from the nipple cavity  19 . In the present example, the substance  24  may be a liquid nutritive substance, such as a water or infant formula based substance, which is provided in adequate supply from a flexible container  47  housed in the bottle cavity  41  to submerge the sensor array  31  sufficiently during deformation of the instrumented nipple  10 A to allow conduction of sound waves between the piezoelectric crystal sensors  32  of the sensor array  31 . 
     As shown in  FIG. 2B , the evaluation apparatus  100 C includes a flexible container  47  including an end portion  48  which defines a container opening  49 . The wall  50  of the flexible container  47  is non-permeable, and the interior surface  51  of the wall  50  defines a container cavity  52 . The end portion  48  of the flexible container  47  is positioned as generally shown in  FIG. 2B  to overlap the end portion  42  of the bottle  40 , such that when the instrumented nipple  10 A is sealably attached to the bottle  40  using the collar  28 , the container cavity  52  is in fluid communication with the nipple cavity  19 . The container cavity  52  may be at least partially filled with the substance  24  before sealing the container cavity  52  in communication with the nipple cavity  19 , such that the evaluation apparatus can be positioned during deformation of the instrumented nipple  10 A, e.g., during a calibration or nutritive sucking event, to flow the substance  24  from the container cavity  52  to the nipple cavity  19  and through the aperture  25 , thereby submerging the sensor array  31  in the substance  24  to allow conduction of sound waves through the substance  24  during nutritive sucking. The first sealed chamber  23  is formed by the cavities  19 ,  52  in fluid communication with each other. Deformation of the instrumented nipple  10 A during nutritive sucking or calibration causes a change in pressure in the first sealed chamber  23 . 
     As shown in  FIG. 2B , a second sealed chamber  46  is defined by the bottle wall surface  45  and the portion of the wall  50  of the flexible container housed in the bottle cavity  41 , such that the first sealed chamber  23  and the second sealed chamber  46  are separated by the flexible container wall  50 , e.g., the flexible wall  50  is in operative communication with both the first and second sealed chambers  23 ,  46 . The flexible container  47  may be configured such that changes in pressure in the first sealed chamber  23 , such as pressure changes occurring due to nipple deformation during nutritive sucking or calibration, may be transmitted through the flexible container wall  50  to proportionally change the pressure in the second sealed chamber  46 . 
     As described for  FIG. 2A , deformation of the instrumented nipple  10 A will result in a deformation of the first sealed chamber  23  resulting in a change in pressure in the first sealed chamber  23  and movement of the flexible container wall  50 , which results in a corresponding change in pressure in the second sealed chamber  46 . The corresponding change in pressure in the second sealed chamber  46  is recorded by the pressure gauge  57 . The pressure data collected by the pressure gauge  57  may be used in conjunction with or independent of the kinematics data collected from the sensor array  31  and provided by the sonomicrometry instrumentation of the sensor data collector/analyzer  59  to evaluate the deformation force (magnitude and direction) being applied to an instrumented nipple  10 A. The NS evaluation apparatus  100 C and instrumented nipple  10 A may be calibrated as shown in and described for  FIGS. 3A and 3B . 
     Referring now to  FIG. 3A , shown is a calibration apparatus  60  which may be used to calibrate an instrumented nipple  10  and/or an evaluation apparatus  100  to calculate the magnitude of deformation force applied to the nipple in relation to the pressure change in the nipple cavity, the depth of deformation D, the sensor output of a sensing device  30  which may be included in the instrumented nipple  10 , and/or the resistive force FR exerted by a compliance element  80  which may be included in the instrumented nipple  10 . As shown in  FIG. 3A , the calibration apparatus  60  may include an indenter  63  operatively connected to the force delivering device  61  and configured to deliver a known calibration force FC to the instrumented nipple  10 . The force delivering device  61  may be configured using any suitable means to deliver a calibration force FC to the instrumented nipple  10 . In one example, the force delivering device  61  may be configured as or include a hand held or mechanically driven force gauge, a force transducer, a strain gauge, a pressure gauge, an accelerometer, or a combination of these. The indenter  63  includes a contact interface  64  for making contact with the instrumented nipple  10 , which may be oriented such that contact interface  64  contacts the tongue facing portion  21  of the instrumented nipple  10  when applying a force to the nipple  10 , where the instrumented nipple  10  may be positioned on a platen  65  with the palate facing portion  20  of the nipple  10  in contact with the platen surface  66 . The contact interface  64  may be configured to provide a predetermined pattern or area of contact with the tongue facing portion  21  of the nipple  10  during force application. In a non-limiting example, the contact interface  64  may be semi-spherical to simulate an infant tongue in contact with the nipple during force application. The instrumented nipple  10  is positioned on the platen  65  such that the palate facing portion  20  of the nipple  10  is in contact with the platen surface  66  during force application, and the platen surface  66  provides an opposing force corresponding to the palate force FP (see  FIG. 1A ) exerted by the subject&#39;s palate when the nipple  10  is positioned in the subject&#39;s mouth in a feeding session. The platen surface  66  may be substantially flat, or in a non-limiting example may be contoured to simulate the palate interface. 
     The force delivering device  61  may include a user interface  62  which may be configured to display the calibration information, including the force F exerted on the instrumented nipple  10  by the indenter  63 , the depth of deformation D, the pressure change in the second sealed chamber  46  measured by the pressure gauge  57 , the sensor data collected from a sensing device  30  included in the instrumented nipple  10  by the sensor data collector/analyzer  59  during a calibration event, the calibration results provided by the processor  58 , etc. In one example, an evaluation apparatus  100  including an instrumented nipple  10  may be positioned relative to the calibration apparatus  60  as shown in  FIG. 3B . The evaluation apparatus  100  may be configured as a NNS or as a NS apparatus, as described for  FIGS. 2A and 2B , respectively. The instrumented nipple  10  may include at least one of a compliance element  80 , as described in further detail herein, and/or at least one sensing device  30 . By way of non-limiting example, the sensing device may be a piezoelectric crystal sensing device  30 A, as described for  FIGS. 1A-2B , or may be another sensing device  30 , as described in further detail herein. In a NNS configuration or other configuration where fluid is not required, for example, as a conducting substance, the evaluation apparatus may be configured without a membrane  22  or flexible container  47  such that the bottle cavity  41  and the nipple cavity  19  may be in fluid communication with each other, and the bottle cavity  41  and nipple cavity  19  together define a sealed chamber, such that the pressure change in the sealed chamber defined by the bottle cavity  41  and nipple cavity  19  may be measured by the pressure gauge  57  in fluid communication with the sealed chamber thus defined. 
     A known calibration force FC may be applied to the instrumented nipple  10  using the force delivering device  61 . Application of the known calibration force FC results in deformation of the instrumented nipple  10  and nipple cavity  19 , which produces a change in the pressure of the first and second sealed chambers  23 ,  46  which is measured using the pressure gauge  57  during force application. Deformation of the nipple  10  by the calibration force FC produces a change in the output of the sensing device  30  in communication with the nipple  10 , and the output of the sensing device  30  is measured and collected using the sensor data collector/analyzer  59 . 
     The calibration graph  70  shown in  FIG. 3B  illustrates an example of sensor signal data (shown as the solid line) and pressure change data (shown by the dashed line) collected during the calibration process corresponding to varying magnitude of applied calibration force FC. Other sensor measurements, such as the deformation distance D, may be collected and analyzed in the calibration process. In a first example, the instrumented nipple  10  and/or the evaluation apparatus  100  may be calibrated using the pressure change data collected by the pressure gage  57  and the applied deformation force data collected from the force delivering device  61  during the calibration sequence to perform the calibration. In another example, the instrumented nipple  10  and/or the evaluation apparatus  100  may be calibrated using the movement measurement output data collected from the sensing device  30  and the applied deformation force data collected from the force delivering device  61  during the calibration sequence to perform the calibration. In another example, the calibration may be performed using the pressure change data, the applied deformation force data and the movement measurement output data to perform the calibration. 
     The calibrated evaluation apparatus  100  may be used during an evaluation sequence, which may be a NS or NNS sucking sequence, to collect data for evaluation of a subject&#39;s tongue movement and/or strength. During an evaluation sequence and over time or at time intervals, movement measurement data may be collected from the sensing device  30  and/or pressure data may be collected from the pressure gage  57 , or both may be collected concurrently or independently. The Table 71 of  FIG. 4A  is an illustrative example of kinematic data collected at defined time intervals during a subject&#39;s evaluation sequence from a sensing device  30 A including a piezoelectric crystal sensor array such as the sensor array  31  shown in  FIGS. 1A-1D . During the evaluation sequence, pressure data may be collected concurrently with collection of sensor data from the sensing device  30 A. 
     Graph  72  of  FIG. 4B  shows an illustrative example of normalized pressure data collected during a sucking evaluation sequence from a first subject and a second subject using a NNS evaluation apparatus, for example, the apparatus  100 B shown in  FIG. 2A , and includes a plurality of sucking cycles, which may also be referred to herein as deformation cycles. In the example shown in graph  72 , the pressure data illustrated by the solid line represents data collected from the NNS evaluation apparatus  100 B used with a first subject, where tongue movement of the first subject may satisfy a tongue movement objective or NNS force or strength threshold (not shown). The pressure data illustrated by the broken line in graph  72  represents data collected from the NNS evaluation apparatus  100 B used with a second subject, where the tongue movement of the second subject may not meet the tongue movement objective or NNS force or strength threshold. The data shown is illustrative and non-limiting. 
     Graph  73  of  FIG. 4C  shows an illustrative example of normalized and non-normalized pressure data collected during a sucking evaluation sequence from a subject using a NS evaluation apparatus, for example, the apparatus  100 C shown in  FIG. 2B , and includes a plurality of sucking cycles, which may also be referred to herein as deformation cycles. In the example shown in graph  73 , the pressure data illustrated by the solid line represents data collected from the NS evaluation apparatus  100 C used with a first subject, where tongue movement of the first subject may satisfy a tongue movement objective or NS force or strength threshold (not shown). The pressure data illustrated by the broken line in graph  73  represents data collected from the NS evaluation apparatus  100 C used with a second subject, where the tongue movement of the second subject may not meet the tongue movement objective or NS force or strength threshold. The data shown is illustrative and non-limiting. 
     The collected data may be analyzed for evaluation and measurement of the tongue movement and/or force exerted by the subject on the instrumented nipple  10  during the stages of sucking, from which measurements of tongue strength such as work performed, impulse, power, sucking frequency, rate of force production, rate of tongue movement, deformation distance, or other strength measures may be derived. Further analysis may include evaluation of sucking frequency and/or rate, rate of exerted force (exerted force measured over time), deformation rate (deformation distance over time) or other parameters measured over the time period of the sucking session which may be used, for example, to quantify fatigue. 
     The evaluation system  105  and evaluation apparatus  100  can be used with a subject in a noninvasive manner to accurately collect, model and quantify the tongue movement, tongue force, and/or sucking behavior of a subject, which may include determining the deformation forces exerted by the subject on the instrumented nipple  10  during an evaluation sequence, which may include a sucking sequence. Both NS and NNS sequences may be evaluated for a subject. In an intervention method  110  illustrated in  FIG. 14  and described in further detail herein, one or more instrumented nipples  10  having a known compliance may be used to evaluate and develop a subject&#39;s tongue strength. 
     Various configurations of instrumented nipples  10 , each having a known compliance, and which may include, by way of non-limiting example, instrumented nipples  10 A . . .  10 H illustrated by  FIGS. 1A-1D  and  5 B- 12 B, may be used in the noninvasive methods described herein to provide a direct measurement of tongue movement and/or force and evaluation of tongue movement and/or strength. Various types of sensors and configurations of sensing devices  30  and/or compliance elements  80  may be used for instrumenting an instrumented nipple  10 . Sensing devices  30  and sensor types may include but not be limited to contact and non-contact strain gages, piezoelectric crystals, piezoelectric films or other piezoelectric material, piezoresistive material, accelerometers, force transducers, microstrain displacement/position sensors, differential variable reluctance transducers (DVTR) and the like. A sensor may be adhered, bonded, glued, inserted within the nipple cavity  19 , sutured or tied to a portion of the nipple, affixed, clamped, fixtured or otherwise attached to or positioned in operative contact or communication with a portion of the nipple such that deformation forces exerted on the nipple may be measured or otherwise evaluated. The sensor or sensing device  30  including the sensor may be configured to provide an output signal, which may be measurable or observable as a sound wave, an electrical signal, an optical signal, a pressure, a strain, a visual indicator or combination of these. An instrumented nipple  10  may include more than one sensor or sensing device  30 , where the plurality of sensors or sensing devices  30  may be arranged in the nipple cavity  19  to measure the deformation force exerted in more than one location in the nipple cavity  19 . The examples of sensor and sensing device types and configurations provided herein are intended to be illustrative and non-limiting. 
     Various types of compliance elements  80  may be used to provide an instrumented nipple  10 . A compliance element  80  may be integral or non-integral to the nipple structure, and may be adhered, bonded, glued, inserted within the nipple cavity  19 , sutured or tied to a portion of the nipple, affixed, clamped, fixtured or otherwise attached to or positioned in operative contact or communication with a portion of the nipple element  11  such that the compliance element  80  modifies the compliance of the nipple element  11  to provide an instrumented nipple  10  having a compliance which is known or determinable by calibration. The compliance element  80  may include or be formed of a deformable material such that the compliance element  80  is deformed as the instrumented nipple  10  is deformed. The deformable material may be a polymer-based material. In one example, the deformable material may be silicone. The deformable material may have defined or known characteristics such that the deformable material is configured to systematically move, strain, or otherwise deform relative to the forces applied to the instrumented nipple  10 , and/or to provide a known resistive force FR. The compliance element  80  may be configured to provide a resistive force FR which may be linear or non-linear. The compliance element  80  may be configured to plastically deform above a predetermined level of applied tongue force FT, to provide a visual indicator. The predetermined level at which the visual indicator is provided may correspond to a tongue movement threshold or tongue strength objective established for the subject related to the evaluation method  110  shown in  FIG. 14 . The tongue movement threshold or tongue strength objective may correspond to the minimum tongue force required for successful NNS or NS sucking or nutritive feeding, successful swallowing, or the like. The examples of compliance element types and configurations provided herein are intended to be illustrative and non-limiting. 
     Referring now to  FIGS. 5A and 5B , a non-instrumented nipple element  11  is shown in  FIG. 5A  and an instrumented nipple  10 B is shown in  FIG. 5B , where each is shown in a sucking condition. The nipple element  11  of  FIG. 5A  includes a tongue facing portion  21  having a wall thickness W1. As shown in  FIG. 5A , in the sucking condition, a tongue force FT1 compresses the non-instrumented nipple element  11  and deforms the tongue facing portion  21  toward the palate facing portion  20 . The magnitude of the deformation resulting from the applied tongue force FT1, which may be measured by a deformation distance D, is D1 in the present example. A resistive force FR1 is exerted by the non-instrumented nipple element  11  in opposition to the tongue force FT1, where the resistive force FR1 is a function of the compliance of the non-instrumented nipple element  11 , e.g., the nipple&#39;s tendency to resist deformation caused by applied forces such as the tongue force FT1. 
     The instrumented nipple  10 B includes a compliance element  80 A which is configured to decrease the compliance of the tongue facing portion  21  of the instrumented nipple  10 B such that the instrumented nipple  10 B exerts a resistive force FR2 in opposition to an applied tongue force FT2. The integral compliance element  80 A is formed by thickening the wall  16  of the tongue facing portion  21  to an effective or total wall thickness W2, such that W2&gt;W1. The compliance element  80 A may be formed by molding the instrumented nipple  10  to provide additional material  26  in the tongue facing portion  21  to form the compliance element  80 A. By way of example, the compliance element  80 A may be provided by adhering, bonding, or otherwise attaching the additional material  26  to the nipple wall surface  17  of the tongue facing portion  21 . The material  26  may be the same material as the nipple element  11 , or may be a different material as required to achieve the desired level of compliance of the instrumented nipple  10 B. The integral compliance element  80 A deforms when the nipple  10 B is deformed. The effective wall thickness W2 increases the resistive force FR2 of the nipple  10 B such that FR2&gt;FR1, and the compliance of the instrumented nipple  10 B is less than the compliance of the non-instrumented nipple element  11  shown in  FIG. 5A . 
     The calibration apparatus  60  may be used to determine the compliance level of the instrumented nipple  10 B relative to the non-instrumented nipple element  11 . For example, the force delivering device  61  may be used to measure a calibration force FC1 required to deform the non-instrumented nipple element  11  to the deformation distance D1, where FC1∝FR1. The force delivering device  61  may then be used to measure a calibration force FC2 required to deform the non-instrumented nipple element  11  to the same deformation distance D1, where FC2∝FR2, and the ratio of FC2/FC1 is proportional to FR2/FR1 to provide a relative indication of the compliance increase of the instrumented nipple  10 B relative to the non-instrumented nipple element  11 . Because the compliance of the instrumented nipple  10 B is less than that of the non-instrumented nipple element  11 , the tongue force FT required to deform the nipple  10 B in a sucking condition is increased from FT1 to FT2. The instrumented nipple  10 B may be used, for example, in the intervention method  110  shown in  FIG. 14 , to exercise and strengthen the subject&#39;s tongue, e.g., to train the subject to achieve the same level of deformation D1 by increasing the subject&#39;s tongue strength from FT1 to FT2. 
     Referring now to  FIGS. 6A and 6B , shown is another example of an instrumented nipple  10 C which includes a sensing device  30 B. The sensing device  30 B includes a sensor  36 , which in the non-limiting example shown may be configured as a strain gage. In use, the sensor  36  is operatively attached to the wall surface  17  of the tongue facing portion  21  of the nipple element  11 , or positioned relative to (in contact with or immediately adjacent to) the wall of the nipple element  11 , such that deformation forces exerted on the nipple wall  16  may be detected by the sensor  36 , thereby providing an instrumented nipple  10 C. Leads  33  are provided in operative communication with the sensor  36  and may be configured such that ends  38  may be operatively connected to a communication interface  35  or to a sensor data collector/analyzer  59 , to provide direct measurement of an output signal provided by the sensor  36  in response to an applied deformation force. In the present example, the sensor  36  is configured as a strain gage operatively attached to the wall surface  17  adjacent the tongue facing portion  21  of the instrumented nipple  10 C. It would be understood that other forms of sensors, included but not limited to piezoelectric crystals, piezoelectric films or other piezoelectric material, piezoresistive material, accelerometers, and force transducers, may be used. As a tongue force TF is applied to the tongue facing portion  21 , the nipple  10  distorts from a resting condition into a sucking condition and the strain gage  36  is deformed to provide an output signal proportional to the applied tongue force TF. The instrumented nipple  10 C may be calibrated such that the output signal can be correlated to the applied tongue force TF. The instrumented nipple  10 C may be used to evaluate tongue movement and/or strength during NNS, and/or may include an aperture  25  for fluid flow through to allow use of the instrumented nipple  10 C for evaluating tongue movement and/or strength during NS. The instrumented nipple  10 C may be used in conjunction with an evaluation apparatus  100 , to provide direct measurement of the tongue force FT exerted on the instrumented nipple  10 C during an evaluation sequence, which may be a sucking sequence. The direct movement measurements of the tongue force FT provided by the sensing device  30 B may be used to measure and evaluate the subject&#39;s tongue strength. Optionally, measurement of pressure changes during the evaluation or sucking sequence may be made using the evaluation apparatus  100  and used in the evaluation of the subject&#39;s tongue movement, strength, and/or sucking capability. 
     As shown in  FIGS. 7A and 7B , an instrumented nipple  10 D may include a sensing device such as the sensing device  30 B shown in  FIG. 6A . The instrumented nipple  10 D may further include a compliance element  80 B made of deformable material which may be positioned in the nipple cavity  19  and in communication with the sensor  36 . The compliance element  80 B may be embedded in, adhered or affixed to the cavity wall  17 , for example, using an adhesive or other means, such as bonding or molding in the compliance element  80 B or otherwise positioning the compliance element  80 B adjacent to or in contact with the cavity wall  17 . A holder  39  may be used to position or support the compliance element  80 B and sensing device  30 B. The compliance element  80 B may be formed of a polymeric material, a natural or synthetic rubber, or other material in any shape or orientation such that the compliance element  80 B in use changes the compliance of the nipple element  11  to provide the instrumented nipple  10 D. The instrumented nipple  10 D may be calibrated to determine its compliance, e.g., the resistive force provided by the instrumented nipple  10 D in a sucking condition. Alternatively, the characteristics of the compliance element  80 B, for example the material, shape, thickness, placement, attachment method, etc., may be known and used in determining compliance. In the example shown, the compliance element  80 B is configured as a polymer strip, which may be a silicone-based material, and is bonded to the cavity wall  17  of the tongue facing portion  21 . The sensing device  30 A includes a strain gage sensor  36  which is affixed to the compliance element  80 B. In use, deformation forces applied to the nipple  10 , such as tongue forces FT exerted on the instrumented nipple  10 D in a sucking condition or calibration forces FC exerted on the instrumented nipple  10 D during calibration, cause the compliance element  80 B to systematically deform and/or move in response to the deformation forces. The deformation or strain of the compliance element  80 B is detected by the sensor  36 , which provides the measured strain as an output signal via leads  33 . The measured strain of the compliance element  80 B in a resting condition and a deformed condition such as a sucking condition may be calibrated such that the instrumented nipple  10 D may be used as a noninvasive means for direct measurement of the deformation force exerted on the nipple, which may be the tongue force of a subject deforming the nipple  10 D during a sucking event, and for evaluation of the subject&#39;s tongue movement and strength. Changing the compliance of the instrumented nipple  10 D using the compliance element  80 B changes the tongue force FT required to deform the nipple  10 D in a sucking condition. By knowing the compliance of the instrumented nipple  10 D including the compliance element  80 B, through calibration or based on the characteristics of the compliance element  80 B, the instrumented nipple  10 D may be used in the intervention method  110  shown in  FIG. 14 , to evaluate, exercise and strengthen the subject&#39;s tongue. 
     In another example shown in  FIGS. 8A and 8B , an instrumented nipple  10 E may include an insert which may include a sensing device such as the sensing device  30 B shown in  6 A in operative communication with a compliance element  80 C made of deformable material which may be positioned in the nipple cavity  19  to provide a resistive force FR to a deformation force exerted on the nipple element  11 . The deformation force may be, for example, a tongue force FT applied to the instrumented nipple  10 E, for example, during a sucking event, or may be a calibration force FC applied to the instrumented nipple  10 E during calibration. In the example shown, the compliance element  80 C is configured as a generally C-shaped element and a resting dimension A1 is the distance between the ends  81 ,  82  of the compliance element  80 C in the resting condition shown in  FIG. 8A . The compliance element  80 C may be formed of a polymeric material, a natural or synthetic rubber, or other material in any shape or orientation such that the compliance element  80 C inserted into the nipple cavity  19  in use changes the compliance of the nipple element  11  to provide an instrumented nipple  10 E. The sensor  36 , which may be configured as a strain gage, is in operative communication with an intermediate portion  83  of the compliance element  80 C. The compliance element  80 C is made of a deformable material, which may be a polymer based material such as silicone. The compliance element  80 C may be positioned relative to, adhered or affixed to the cavity wall  17  so as to deliver a resistive force FR to the instrumented nipple  10 E. The instrumented nipple  10 E is shown in a resting condition in  FIG. 8A  and in a deformed, or sucking condition in  FIG. 8B . In the resting condition, the compliance element  80 C is configured to define a resting dimension A1 which corresponds to a resting strain which may be output as a resting strain signal by the sensor  36  through the leads  33 . 
     As shown in  FIG. 8B , during deformation of the instrumented nipple  10 E, for example, by a tongue force FT, the nipple element  11  is deformed and the nipple wall  16  compresses the compliance element  80 C such that the intermediate portion  83  is deformed and strained. The sensor  36  gauges the material strain of the compliance element  80 C during deformation and outputs the strain as a measurable signal. During deformation, the ends  81 ,  82  are compressed together to define a deformation dimension A2 which is proportional to the deformation depth D and the strain of the intermediate portion  83 . The instrumented nipple  10 E may be calibrated such that the deformation force FT and the deformation distance D corresponding to the strain measurement may be determined. The compliance element  80 C may be configured to provide a resistive force which is known based on characteristics of the compliance element  80 C which may include material, shape, dimensions, etc, or which may be determined by calibration, such that the instrumented nipple  10 E may have a known compliance. The deformation or strain of the compliance element  80 C is detected by the sensor  36 , which provides an output signal via leads  33 , thereby providing a means for direct measurement of the deformation force exerted on the nipple  10 E, which may be the tongue force FT of a subject deforming the nipple  10 E, for example, during a sucking event or other tongue movement evaluation event. The movement measurements provided by the output signals of the sensing device  30 B may be used in evaluation of the subject&#39;s tongue movement and strength. Changing the compliance of the instrumented nipple  10 E using the compliance element  80 C changes the tongue force FT required to deform the nipple  10 E in a sucking condition. By knowing the compliance of the instrumented nipple  10 E including the compliance element  80 C, the instrumented nipple  10 E may be used in the intervention method  110  shown in  FIG. 14 , to evaluate, exercise and strengthen the subject&#39;s tongue. The example of a compressible compliance element  80 C is not intended to be limiting, and other configurations may be possible. For example, the compliance element may be generally ring shaped. 
     In another example shown in  FIGS. 9A and 9B , a compressible compliance element  80 D is shown in operative communication with an intermediate device  37 , such that the compliance element  80 D and intermediate device  37  may be inserted into the nipple element  11  to provide an instrumented nipple  10 F. In the example shown, the compliance element  80 D is configured as a generally V-shaped insert where a resting dimension B1 is the distance between the ends  81 ,  82  of the compliance element  80 D in the resting condition shown in  FIG. 9A . The compliance element  80 D may be formed of a deformable material which may be a polymeric material, a natural or synthetic rubber, a metallic material or other material or combination of materials in a shape or orientation such that the compliance element  80 D inserted into the nipple cavity  19  in use changes the compliance of the nipple element  11  to provide an instrumented nipple  10 F. The compliance element  80 D may be positioned relative to, adhered or affixed to the cavity wall  17  so as to deliver a resistive force FR to the instrumented nipple  10 F. The instrumented nipple  10 F is shown in a resting condition in  FIG. 9A  and in a deformed, or sucking condition in  FIG. 9B . In the resting condition, the compliance element  80 D is configured to define a resting dimension B1 which corresponds to a resting state of the intermediate device  37 . As shown in  FIG. 9B , during deformation of the instrumented nipple  10 F, for example, by a tongue force FT, the nipple element  11  is deformed and the nipple wall  16  compresses the compliance element  80 D such that the intermediate portion  83  is deformed and strained. During deformation, the ends  81 ,  82  are compressed together to define a deformation dimension B2 which is proportional to the deformation depth D and the strain of the intermediate portion  83 . 
     The intermediate device  37  is in operative communication with an intermediate portion  83  of the compliance element  80 D, and may be configured to transfer or transmit a change in the compliance element  80 D during deformation of the nipple  11  by a deforming force such as a tongue force FT. The change in the compliance element  80 D, which may be referred to herein as a deformation change, may be in the example shown in  FIGS. 9A and 9B , a change in material strain, a change in the deformed position of the intermediate portion  83  relative to the resting condition of the intermediate portion  83 , or a stress imposed by movement of the compliance element  80 D on the intermediate device  83 . The intermediate device  37  may be configured, for example, as a triggering device, a connector, a mechanical pulley or cam system, an electrical, pneumatic, magnetic, hydraulic or optical switch, sensor, cantilever, or actuator, and the deformation change may be the response of the intermediate device  37  to deformation of the nipple element  11 . The deformation change may be measurable as a force, displacement, magnetic property, pressure, optical characteristic, etc. as defined by the configuration of the intermediate device  37 . In one example, the intermediate device  37  may be configured as a cantilever positioned relative to the nipple element  11  such that the cantilevered intermediate device  37  may be displaced by deformation of the nipple element  11 . A sensing device  30 , which may include, for example, a linear displacement sensor, may be in communication with the cantilevered intermediate device  37  to sense the displacement (deformation change) of the cantilevered intermediate device  37  and provide an output in response to the displacement (deformation change). In one example, the intermediate device  37  may include a piezoelectric material configured to sense deformation changes in the compliance element  80 D. The intermediate device may be in communication with a sensing device  30  or data collector/analyzer  59 , such that the intermediate device may be actuated by the deformation change of the compliance element  80 D to transmit or transfer the deformation change to the sensing device  30  or data collector/analyzer  59  as an output, where the output may be in the form of an electrical, magnetic, sound, optical, or pneumatic signal, a displacing force, stress or strain provided as an input to the receiving sensor  36 , sensing device  30  or data collector/analyzer  59 . 
     The instrumented nipple  10 F may be calibrated such that the output provided by the intermediate device  37  in response deformation of the compliance element  80 D by a known deformation force FT may be determined. The compliance element  80 D may be configured to provide a resistive force FR which is known based on characteristics of the compliance element  80 D which may include material, shape, dimensions, etc, or which may be determined by calibration, such that the instrumented nipple  10 F may have a known compliance. The deformation of the compliance element  80 D is transmitted via the intermediate device  37  to, for example, a sensing device  30 , thereby providing a means for direct measurement of the deformation force exerted on the nipple  10 F and/or evaluation of a subject&#39;s tongue movement and/or strength when the deformation force exerted on the nipple is the tongue force FT exerted on the nipple  10 F by the subject. 
     The example shown in  FIGS. 9A and 9B  is non-limiting, and other configurations of an instrumented nipple  10  including a compliance element  80  and intermediate device  37  are possible. For example, an intermediate device  37  configured as a non-contact optical sensor may be used in combination with the compliance element  80 C shown in  FIGS. 8A and 8B , where the intermediate device  37  is configured to optically sense the deformation distance A and to provide a signal corresponding to the measured deformation distance A to a data collector  59  in communication with the intermediate device  37 . 
     Referring now to  FIGS. 10A-10C , the compliance element  80 D may be configured to plastically deform at a predetermined force, to provide a visual indicator that a deformation force exceeding a predetermined force threshold has been exerted on the instrumented nipple  10 F, thus allowing noninvasive evaluation of the deformation force exerted on the nipple without using an additional sensing device  30 . Referring now to  FIG. 10A , shown is a compliance element  80 D in a resting condition in the nipple cavity  19 . The compliance element  80 D may be configured as described for  FIGS. 9A and 9B , and may be characterized by a predetermined elastic limit, such that when the compliance element  80 D is subjected to a compressive deformation force FT exceeding the predetermined elastic limit, which may correspond to compression of the compliance element  80 D to a plastic deformation distance B3, the compliance element  80 D undergoes plastic deformation such that upon cessation of or reduction of the deformation force below the plastic limit, the compliance element  80 D remains permanently deformed and does not return to the resting deformation state defined by the resting dimension B1. In the example shown in  FIG. 10C , the permanently deformed compliance element  80 D may separate from the cavity wall  17  to provide a visual indicator that the predetermined elastic limit has been exceeded. The plastically deformed compliance element  80 D may be measured to determine the deformation dimension B3, where the amount of plastic deformation corresponding to the deformation dimension B3 may be calibrated to indicate the maximum deformation force exerted on the instrumented nipple  10 F and compliance element  80 D. The example illustrated by  FIGS. 10A-10C  is intended to be non-limiting, and the compliance element  80  may be configured to provide other visually discernible indications, such as changes in color, texture or shape, that a predetermined force limit has been exceeded by the deformation force, such that the compliance element  80  may additionally function as a sensing device  30 . 
       FIGS. 11A-11C  show another example of an instrumented nipple  10 G including a compliance element  80 E. The generally conical compliance element  80 E is configured such that the outer surface  84  of the compliance element  80 E substantially conforms to a circumferential portion of the inner surface  17  of the nipple cavity  19  when inserted into the nipple element  11  having a nipple wall thickness Wn, to provide an instrumented nipple  10 G characterized by a resistive force FR. The compliance element  80 E includes an insert cavity  85  defined by the insert wall  86 , wherein the insert wall may be characterized by an insert thickness Wi. The compliance of the instrumented nipple  10 G is a function of the compliance element  80 E and compliance of the nipple element  11 , which in combination provide a compliance proportional to the total wall thickness Wt≅Wn+Wi. The total wall thickness Wt may also be referred to as the effective wall thickness of the instrumented nipple  10 . The compliance of the instrumented nipple  10 G may be established by calibration using a calibration apparatus such as the calibration apparatus  60  shown in  FIG. 3A , or may be determined based on the known characteristics of the nipple element  11  and compliance element  80 E. The compliance element  80 E may be formed of a deformable material, which may be a polymer based material such as a silicone. The compliance element  80 E may be removably positioned in the cavity  19 , or may be adhered or otherwise affixed to the cavity surface  17  or nipple wall  16 . The compliance element  80 E may include an aperture  87 , such that the instrumented nipple  10 G may be used for NS and NNS configurations. It would be understood that a series of compliance elements  80 E having increasing wall thicknesses Wi1, Wi2 . . . Win may be used in sequence, in conjunction with the evaluation and intervention method  110  shown in  FIG. 14  to exercise and increase a subject&#39;s tongue strength. 
       FIGS. 12A and 12B  show an example configuration of an instrumented nipple  10 H including a compliance element  80 F. The semi-conical or partially conical compliance element  80 F is configured such that the outer surface  84  of the compliance element  80 F substantially conforms to the tongue facing portion  21  of the nipple cavity  19  when inserted into the nipple element  11  having a nipple wall thickness Wn, to provide an instrumented nipple  10 H characterized by a resistive force FR. The compliance element  80 F includes an insert cavity  85  defined by the insert wall  86 , wherein the insert wall may be characterized by an insert thickness Wi. The compliance of the instrumented nipple  10 H is a function of the compliance element  80 F and compliance of the nipple element  11 , which in combination provide a compliance proportional to the total wall thickness Wt≅Wn+Wi, where Wt is the effective wall thickness of the instrumented nipple  10 H. The compliance of the instrumented nipple  10 H may be established by calibration using a calibration apparatus such as the calibration apparatus  60  shown in  FIG. 3A , or may be determined based on the known characteristics of the nipple element  11  and compliance element  80 F. The element  80 F may be formed of a deformable material, which may be a polymer based material such as a silicone, a natural or synthetic rubber, etc. The compliance element  80 F may be removably positioned in the cavity  19 , or may be adhered or otherwise affixed to the cavity surface  17  or nipple wall  16 . The compliance element  80 F may be configured and/or positioned in the nipple cavity  19  such that flow of fluid through the nipple aperture  25  is not restricted, and such that the instrumented nipple  10 H may be used for NS and NNS configurations. It would be understood that a series of compliance elements  80 F having increasing wall thicknesses Wi1, Wi2 . . . Win may be used in sequence, in conjunction with the evaluation and intervention method  110  shown in  FIG. 14  to exercise and increase a subject&#39;s tongue strength. 
     Other combinations and configurations of instrumented nipples  10  are possible. For example, a sensing device  30  and/or intermediate device  37  may be included in each of the instrumented nipples  10 F,  10 G,  10 H to enable direct measurement of deformation of the instrumented nipple  10  and/or compliance element  80 , which may be, as described previously, a measurement of strain, displacement, or other quantifiable characteristic of the deforming compliance element  80 . An instrumented nipple  10 , may, by way of non-limiting example, be configured as an instrumented nipple  10 A . . .  10 H described herein, or otherwise configured within the scope of the descriptions provided herein, and may be used in conjunction with an evaluation apparatus  100  and/or evaluation system  105 , for the measurement, evaluation and/or improvement of a subject&#39;s tongue movement and/or strength. Optionally, measurement of changes in pressure during NS and/or NNS using the evaluation apparatus  100  and/or the evaluation system  105  may be performed, and the pressure data collected and included in the analysis and evaluation of tongue movement and/or strength. 
     Referring now to  FIGS. 13A-13C , shown is a schematic illustration of a tongue movement evaluation apparatus  100 D including a coupling device  90  and an instrumented nipple  10  or nipple element  11 . The instrumented nipple  10  includes at least one of a sensing device  30  in communication with a compliance element  80 . In one example, the coupling device  90  may include a sensing device  30 , for example, an optical sensing device, configured to measure deformation of the nipple element  11 . In another example, the coupling device may include a sensing device  30  in communication with a compliance element  80  via an intermediate device  37 . In the example shown, the coupling device  90  is configured at a first end  91  to interface with a bottle  40 . The bottle  40  may be a commercially available, e.g., standard, infant feeding bottle (baby bottle), or may be a bottle  40  configured as shown in and described for  FIGS. 2A and 2B . In one example, the first end  91  may define a plurality of threads for engaging the threaded end  42  (see  FIG. 2A ) of the bottle  40 , to create a sealed interface between the bottle  40  and coupling device  90 . The example provided herein is not limiting, and other configurations of the first end  91  may be used to create a sealed interface between a container or bottle  40  and the coupling device  90 . For example, the first end  91  may be configured to snap on, clip to, or create an interference fit with the container  40  to provide a sealed interface. 
     The coupling device  90  is configured at a second end  92  to interface with a collar  28 . The collar  28  may be, in the example shown, a standard infant bottle collar or ring threadable onto the end portion  42  to retain the instrumented nipple  10  in sealing contact with the coupling device  90 . In one example, the second end  92  may define a plurality of threads for engaging the collar  28 , where the plurality of threads may be configured substantially similar to the plurality of threads of a standard infant feeding bottle. The coupling device  90 , thus configured, is readily attachable to a standard, e.g., commercially available, infant feeding bottle  40  and bottle collar  28 . As shown in  FIG. 13B , the first end  92  of the coupling device  90  may define a cavity  94  of sufficient depth to receive a nipple element  11  including an extension  27 . In a non-limiting example, the nipple element  11  including the extension  27  may be configured as a standard, e.g., commercially available pacifier, such as a Soothie® pacifier, such that the evaluation apparatus  100 D may be assembled using the coupling device  90 , an insert which may be at least one of a sensing device  30  and a compliance element  80 , and a commercially available bottle  40 , collar  28  and nipple element  11 , which may be a standard pacifier to provide a NNS configuration, or standard feeding nipple to provide a NS or NNS configuration. In a NS configuration, fluid may be flowed from a bottle  40  connected to the first end  91  of the coupling  90  through a cavity  97  defined by an inner wall  95  of the coupling  90 , through an end cavity  94  defined by the second end  92  of the coupling  90 , and through an aperture  25  of the nipple element  11 . The example provided herein is not limiting, and other configurations of the second end  92  may be used to position the nipple element  11  relative to the coupling device  90  and/or to retain the nipple element  11  in sealing contact with the coupling device  90 . For example, the second end  92  may be configured with a recessed portion or groove into which the flange  15  of the nipple element  11  may be inserted or retained. The nipple element  11  may be configured to be extended over the second end  92  to create an interference fit with the coupling device  90  to provide a sealed interface without requiring the collar  28 . The collar  28  may be configured to snap or clip onto the second end  92  or to otherwise be retained by the second end  92 . 
     In a NNS configuration, the evaluation apparatus  100 D may be used without a bottle  40 . A plug  98  (see  FIG. 13C ) may be provided to enclose the first end  91  of the coupling device when used without a bottle  40 , to protect the threaded interface, prevent contamination of or damage to the interior cavities  94 ,  97  of the coupling device  91 , the receiver  96  or other components such as a sensing device  30 , etc. housed therein. The plug  98  may be configured to sealably attach to the first end  91 , to provide a sealed chamber defined by the plug  98 , inner wall  95  of the coupling device  90 , and nipple wall  16 . 
     As shown in  FIGS. 13A-13B , the coupling device  90  may be in communications with a sensing device  30 , an intermediate device  37 , and/or a receiver  96  to receive and transmit data and/or sensor signals to, for example, the data collector/analyzer  59  or a portable data storage device (not shown) such as a SIM card, flash drive, etc. which may include RAM or flash memory and be used to transfer the collected data to the data collector/analyzer  59 . The communications interface  35  may be configured to transmit output signals from a sensing device  30  or intermediate device  37  included in the evaluation apparatus  100 D or received via the receiver  96  of the coupling device  90 . In one example, the communications interface  35  may be configured for wireless transmission of the sensor signals to the data collector/analyzer  59  using any suitable means of wireless transmission such as Bluetooth®, RFID, Wi-Fi, ZigBee® or other wireless methods. 
     The coupling device  90  may include a user interface  75 , which may include a display and/or input/output interface for visually, audibly, or textually communicating data, analysis results, messages, instructions, alerts, etc. The coupling device  90  may include a transducer  76 , which may be configured, for example, to convert an input signal received from a sensing device  30 , intermediate device  37 , pressure sensor  79 , into an output signal to be provided to the communications interface  35 , stored in a memory  78 , displayed via the user interface  75 , etc. The input signal may be an electrical, mechanical (force, stress, strain), electromagnetic, optical, chemical, pressure, or acoustic signal which may be converted by the transducer  76  into an output signal which may be, in a non-limiting example, an electrical, visual or audible signal. The coupling device  90  may include a power source  77 , which may be a battery or power input interface, and a memory  78  configured as one or more of Read Only Memory (ROM), Random Access Memory (RAM), electrically-erasable programmable read only memory (EEPROM), etc., of a size and speed sufficient for executing the functions performed by the coupling device  90 . 
     The coupling device  90  may include a receiver  96  which may be configured to position, connect to, and or receive a sensing device  30 , intermediate device  37  or holder  39 . The receiver  96  may be in operative communication with one or more of the communications interface  35 , the user interface  75 , the transducer  76  and the memory  78  and may be configured to transmit data and/or signals between the sensing device  30  or intermediate device  37  and one or more of these. The sensing device  30  may be integrated into the receiver  96  and/or coupling  90  as shown in  FIG. 13B , and output signals may be received from a compliance element  80  via an intermediate device  37  in communication with the compliance element  80  and the integrated sensing device  30 . 
     The coupling device  90  may optionally include a pressure gauge  79  in communication with one of the cavities  94 ,  97  defined by the coupling  90 . A sealed chamber may be formed by the bottle cavity  41 , coupling cavities  97 ,  94  and nipple cavity  19 , such that the pressure gauge  79  in communication with the sealed chamber thus formed by the connected cavities  19 ,  41 ,  94 ,  97  can be used to measure pressure changes in the sealed chamber resultant from tongue movement of a subject, for example, during a sucking event, and the pressure measurements used in evaluating the tongue movement and/or tongue strength of the subject. Alternatively, the plug  98  may be sealably attached to the first end  91  of the coupling device  90  to form a sealed chamber defined by the cavities  19 ,  94  and  97  to measure pressure changes in the sealed chamber thus formed using the pressure gauge  79 . 
     The tongue movement evaluation apparatus  100 D including the coupling device  90  may be assembled in various configurations and combinations of sensing devices  30 , compliance elements  80 , intermediate devices  37 , etc., including but not limited to the configurations shown in  FIGS. 13A-13C . Referring to  FIG. 13B , the evaluation apparatus  100 D includes a nipple element  11  configured as a pacifier which is positioned in sealing contact with the second end  92  of the coupling  90 , and retained in position by the collar  28 , to provide a NNS configuration. In a NNS configuration, a bottle  40  or plug  98  may be optionally attached to the first end  91 . Alternatively, a feeding nipple element  11  including an aperture  25  may be substituted for the pacifier nipple element to provide a NS configuration. In the NS configuration, a bottle  40  containing a fluid  24  may be attached as shown in  FIG. 13A . A compliance element generally indicated at  80  is positioned in the nipple cavity  19  to provide an instrumented nipple  10 . The compliance element  80  may be, by way of non-limiting example, configured as a compliance element  80 A,  80 B,  80 C or  80 D. The coupling device  90  includes an integrated sensing device  30  for receiving signals from the compliance element  80  via an intermediate device  37  which is in operative communications with the compliance element  80  and the integrated sensing device  30 . In one example, the intermediate device  37  may be connected to the integrated sensing device  30  via the receiver  96 . 
     A holder  39  may be provided to support or position the intermediate device  37  and/or the compliance element  80  with respect to the nipple element  11  and the receiver  96 . The receiver  96  may be configured to receive the holder  39  in an oriented position relative to the nipple element  11 , and/or a tongue facing portion  21  of the nipple element  11 . The compliance element  80  may be oriented or positioned to be deformed by and/or sense a deformation force exerted on the nipple element  11 . The deformation force may be a tongue force FT exerted on the tongue facing portion  21  of the instrumented nipple  10  by a subject during a sucking session, such that noninvasive direct measurement of the deformation force may be made using the evaluation apparatus  100 D to evaluate the tongue movement, tongue strength and/or sucking capability of the subject. 
     In another example configuration shown in  FIG. 13C , the evaluation apparatus  100 D may include a sensing device  30 B and compliance element  80 B which is inserted into the nipple element  11  to provide an instrumented nipple  10 . The sensing device  30 B may include a strain gage sensor  36  operatively attached to the compliance element  80 B to measure strain of the compliance element  80 B during deformation of the nipple element  11 . The leads  33  attached to the strain gage sensor  36  may be operatively attached to the receiver  96  to provide strain data via the receiver  96  to the memory  78 , user interface  75  and/or communications interface  35 . The sensing device  30 , or a portion thereof such as the leads  33 , may optionally be positioned or fixtured using a holder  39 . The receiver  96  may be adapted to receive the holder  39  and the leads  33 . 
     The coupling device  90  may include a plurality of receivers  96  in communication with the communication interface  35 , such that more than one sensing device  30 , compliance element  80 , and/or intermediate device  37  may be included in the evaluation apparatus  100 D, for example, when it may be desirable to measure the deformation force in more than one location within the nipple element  11 . 
     In use, an evaluation apparatus kit (not shown) may be provided including the coupling device  90  and one or more inserts consisting of at least one of a sensing device  30  and compliance element  80 . The kit may include a plurality of compliance elements  80 , each having a different known compliance, for use with the intervention method  110  shown in  FIG. 14 . The kit elements, e.g., the coupling device  90  and insert may be combined with a standard nipple element  11  and/or bottle  40  to provide an evaluation apparatus  100 D. The kit and/or the some or all of the kit elements may be provided in a sterilized condition. 
     Referring now to  FIG. 14 , a method generally indicated at  110  is illustrated for the evaluation of tongue movement and/or tongue strength of a subject using an evaluation apparatus  100  and for providing an intervention to increase the tongue strength of the subject using one or more instrumented nipples  10  to exercise the subject&#39;s tongue. The compliance and resistive force of the instrumented nipple  10  may be selected or configured based on the measured tongue movement and/or strength of the subject, and a series of instrumented nipples  10  of differing compliance may be used in the intervention method and presented to the subject in order of decreasing compliance using the instrumented nipple  10  as a pacifier (NNS) or feeding bottle nipple (NS) to strengthen the tongue muscle, e.g., increase the tongue force exerted by the subject. Similar to exercising any muscle of the body, the tongue can be strengthened through resistance training Resistive force FR can be applied to the tongue via the instrumented nipple  10  during sucking Instrumented nipples  10  of increasing (stiffer) compliance can be introduced in subsequent evaluation sequences (pacifier or feeding sessions) as the tongue muscles progress and become stronger. 
     In a first step  111  of the method  110 , an initial sucking session is conducted with a subject using an evaluation apparatus  100  which may include a nipple  10  of known compliance and/or a sensing device  30 . The subject may be a preterm infant. The evaluation apparatus  100  may be configured as described herein such that noninvasive direct measurement of the deformation force, e.g., the tongue force FT exerted by the subject on the nipple element  11  of the evaluation apparatus  100  is obtained. The tongue force FT may be measured at specific points during a sucking cycle, using an initial insert including a sensing device  30 , for example, and/or a compliance element  80  configured to provide an initial resistive force. Other measurements collected during the first step  111  may include the amount of sucking cycles completed and/or volume of fluid expelled from the nipple  10  during the feeding session. 
     At a second step  112 , the tongue movement and/or tongue strength of the subject is evaluated using the data monitored or collected during step  111 . Evaluation of tongue movement and/or tongue strength may include analysis of the force pattern during the evaluation sequence, which may be a sucking sequence, measurement of deformation of the nipple element, frequency and rate change analysis, calculation of strength parameters such as power, impulse and work, etc. For example, the amount of sucking (deformation) cycles completed and/or volume of fluid expelled from the nipple  10  during the feeding session of step  111  may be used to calculate the amount of work performed by the subject&#39;s tongue during the feeding session. Measurements of the tongue force FT at specific points during the sucking or deformation cycle may be used to calculate impulse and power capabilities of the subject&#39;s tongue. Sucking frequency and rate, and/or the rate of force development over the sucking or evaluation sequence may be analyzed to evaluate fatigue or stamina. 
     At step  113 , a comparison of the subject&#39;s strength level determined at step  112  to a tongue movement objective established for the subject is made. If the tongue movement objective has been met, the method continues to step  114 , and rehabilitation and/or intervention is completed. Optionally, the intervention may continue even though the tongue movement objective has been met, by returning from step  114  to step  111  periodically to conduct an evaluation session to monitor whether the subject&#39;s tongue movement capability has been maintained, e.g., continues to meet the objective. If, at step  112  it is determined that the subject has not met the tongue movement objective, the method continues to step  115 , where the evaluation apparatus  100  may be modified to include an instrumented nipple  10  having less compliance than the previous instrumented nipple  10 , e.g., having greater resistive force, to exercise and develop the subject&#39;s tongue movement and strength. By way of non-limiting example, the evaluation apparatus  100  and/or instrumented nipple  10  may be modified to include another insert, which may be referred to herein as a subsequent insert, which may be configured to provide a resistive force different from, and typically greater than, the insert used for the initial evaluation session. The method returns to step  111  and a subsequent evaluation session is conducted with the subject using the evaluation apparatus  100  including the instrumented nipple  10 , which may include a subsequent insert having a different or decreased compliance than the initial insert. The method continues with conducting subsequent evaluation sessions and evaluating the output from the subsequent sessions until the subject has achieved the tongue movement objective or strength threshold established for the subject. A series of instrumented nipples  10  or subsequent compliance elements  30 , each having increasing resistive force (decreasing compliance), may be used in conjunction with the method  100  to exercise and increase the strength of the subject&#39;s tongue during subsequent evaluation sessions, until the tongue movement objective and/or strength threshold is met. 
     The configurations of the instrumented nipple  10 , sensing device  30 , compliance element  80  and evaluation apparatus  100  shown in the figures are not intended to be limiting. For example, the compliance element  80  and/or sensing device  30  may be configured to measure or indicate deformation using other characteristics or methods, which may include chemical, electrical, physical, or any other material property change such as color, transparency, etc. Other methods of deformation evaluation include but are not limited to visual inspection, chemical testing, material measurement, fluid displacement, shape analysis and pressure measurement. The compliance element  80  may be configured to include non-polymeric materials, including metallic materials, composites, and multi-layer materials. 
     The detailed description and the drawings or figures are supportive and descriptive of the invention, but the scope of the invention is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for practicing the invention defined in the appended claims.