Abstract:
A hearing screener apparatus is disclosed and may include a housing and a testing probe operatively coupled to the housing. The testing probe may generate electrical signals based on otoacoustic emissions of the inner ear of a test subject, when the testing probe is inserted into the ear canal of the test subject. The hearing screener apparatus may also include a housing, a digital signal processor (DSP) within the housing, and a testing probe operatively coupled to the housing. The DSP may generate measurement data based on the electrical signals. At least one microphone may be mounted with the testing probe for generating the electrical signals based on the otoacoustic emissions. The testing probe may be vibrationally isolated from the housing. The testing probe may be elastically coupled to the housing. The hearing screener apparatus may also include an isolation body elastically coupled between the testing probe and the housing.

Description:
This application is a continuation of U.S. application Ser. No. 09/973,129 filed Oct. 9, 2001, now U.S. Pat. No. 6,702,758 which is a continuation of U.S. application Ser. No. 09/285,938 filed Apr. 2, 1999, now U.S. Pat. No. 6,299,584 issued Oct. 9, 2001, which is a continuation-in-part of U.S. application Ser. No. 08/832,277 filed Apr. 3, 1997, now U.S. Pat. No. 5,954,669 issued Sep. 21, 1999 . The above-referenced applications and patents are hereby incorporated herein by reference in their entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to hearing test devices and more specifically to an infant hearing screener which uses distortion-product otacoustic emissions (DPOAE) to determine the function of the outer hair cells, which is an indication of middle-ear function. For example, the absence of DPOAE indicates a possible hearing loss. 
     The otacoustic emissions produced by a healthy ear are extremely small in magnitude. The emissions typically range from −10 db SPL to +20 db SPL. Any kind of extraneous noise introduced into the ear canal or measurement system can mask these emissions and give a false negative response. The microphone must have a very low internal noise level to discriminate the emissions from the system noise. All existing equipment for testing for DPOAE uses a probe which seals into the ear canal and is attached to the measurement equipment through a cable. This type of system is not practical in an infant screener for several reasons. 
     These reasons include the fact that an infant&#39;s ear canal is very small, and as a result, it can be quite difficult to seal a probe into such a small canal. any pull on the probe from the attached cable can break the seal or pull the probe out of the canal. In addition, the time required to place a probe in the infant&#39;s ear canal significantly slows down the testing process. Typically, the infant is asleep when the testing is performed so that movement is minimal. The process of putting the probe into the infant&#39;s ear canal in a manner so that it stays for the duration of the test often wakes the infant which, of course makes the test difficult or impossible to perform. 
     While a hand-held screening device alleviates many of the above discussed problems, implementation of such a device has inherent problems which must be overcome to provide an effective hearing measurement device. One such problem results from the vibrational noise generated by the tester&#39;s hand during the testing. This noise is transmitted through the device and into the microphone which prevents accurate measurements. Holding a conventional probe to the ear canal creates a noise level that completely masks any emissions that could otherwise be detected. 
     Another problem is the difficulty in achieving a consistent seal to the infant&#39;s ear canal. Difficulty in maintaining the seal results from minor movements of the infant&#39;s head and/or the tester&#39;s hand. 
     Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is related to an hearing screener that uses distortion-product otacoustic emissions (DPOAE) to determine the function of the outer hair cells within the middle ear structure. The function of the outer hair cells is an indication of middle-ear function; the absence of DPOAE indicates a possible hearing loss. 
     In one embodiment, the screener is hand-held device that couples to the infant&#39;s ear to perform DPOAE testing. The device creates tones and administers them to the ear canal through two receivers. The emissions are then picked up through a low-noise microphone, and analyzed by a built-in digital signal processor (DSP). The result is displayed on a liquid crystal display (LCD) and can be printed by infrared link to a separate hand-held printer. 
     Aspects of the present invention may be found in a hearing screener apparatus that comprises a housing, a testing probe operatively coupled to the housing, and one or more microphone(s). In one embodiment, the microphone has a noise floor substantially similar to an industry standard microphone when the housing is grasped by a user. In another embodiment, the microphone has a noise floor of at least approximately 15 dB lower when the housing is grasped by a user than when the testing probe is grasped by a user. 
     The microphone(s) may be mounted with the testing probe, for example, and the testing probe may be vibrationally isolated from the housing. In one embodiment, the testing probe is elastically coupled to the housing. In addition, the hearing screener apparatus may further comprise an isolation body elastically coupled between the testing probe and the housing. The hearing screener apparatus may also comprise an ear tip mounted on the testing probe for acoustically sealing the ear canal of a test subject. 
     These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1A  is a side view in cross-section of an embodiment of the hearing screener arranged in a patient&#39;s ear canal. 
         FIG. 1B  is a side view in cross-section of an embodiment of the hearing screener arranged in a patient&#39;s ear canal. 
         FIG. 2  is an exploded cross-sectional side view of an embodiment of the present invention. 
         FIG. 3  illustrates a cross-sectional side view of an embodiment of a hearing screener of the present invention. 
         FIG. 4A  is a cross-sectional view of a portion of the hearing screener taken along line A-A of  FIG. 2 . 
         FIG. 4B  is a cross-sectional view of a portion of the hearing screener taken along line B-B of  FIG. 2 . 
         FIG. 5  is a graph illustrating various microphone noise floor levels of the present invention. 
         FIGS. 6 and 7  illustrate another embodiment of the hearing screener built in accordance with the present invention. 
         FIG. 8  is an exploded view of the hearing screener of  FIGS. 6 and 7 . 
         FIGS. 9A ,  9 B and  9 C illustrate mounting of an isolation body or assembly onto a housing of the screener in accordance with the present invention. 
         FIG. 10  illustrates more detail of the isolation body or assembly wherein a cylinder is mounted onto a spring in accordance with the present invention. 
         FIGS. 11A ,  11 B and  11 C illustrate mounting of a testing probe on a spring of the isolation body or assembly in accordance with the present invention. 
         FIGS. 12A and 12B  illustrate additional detail of a removable probe tip of the testing probe in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A hearing screener apparatus which uses distortion product otacoustic emissions (DPAOE) to determine the function of the outer hair cells, which is an indicator of middle ear function, is provided. The hearing screener is preferably a hand-held device that couples to an infant&#39;s ear to effectively perform DPAOE testing for possible hearing loss. An embodiment of the screener includes an assembly to maintain sealing contact in the ear canal of the patient as well as isolating vibrational noise from their microphone assembly caused by the tester. 
     Referring now to the figures,  FIG. 1A  is a side view in cross-section of an embodiment of the hearing screener arranged in a patient&#39;s ear canal.  FIG. 1B  is a similar side view of the hearing screener arranged at a different angle of attack into the patient&#39;s ear canal. An embodiment of the hearing screener is referenced generally at  100 . A patient&#39;s ear  105  is also illustrated. The hearing screener  100  includes a testing probe indicated at  110 . The testing probe  110  includes an ear tip  115 . The ear tip  115  is arranged at the entrance of an ear canal  120  as shown in  FIGS. 1A and 1B . As illustrated, the ear tip  115  includes a curved flange  125  to effectively seal the ear canal  120 , thus effectively coupling the testing probe  110  of the hearing screener  100  with the patient&#39;s ear  105  so that proper testing can be performed. 
       FIGS. 1A and 1B  also include an isolation body  130  and a housing  140 . Also, a connection  150  is illustrated. The components of the hearing screener  100  are described in more detail below with reference to  FIGS. 2 and 3 . 
       FIG. 2  illustrates an exploded side view of an embodiment of the hearing screener  100  of the present invention. For clarity, the housing  140  is not shown in  FIG. 2 . As discussed above, the hearing screener  100  includes the testing probe  110 , the isolation body  130  and a cylindrical coupling sleeve  160  disposed between the probe  110  and the body  130 . 
     Proceeding from left to right in  FIG. 2 , the hearing screener  100  comprises the ear tip  115  having the curved flange  125  to enable proper sealing within a patient&#39;s ear canal as illustrated in  FIGS. 1A and 1B  and described above. The curvature of the flange  125  permits the ear tip  115  to be arranged at various angles in the patient&#39;s ear canal  120  as shown in  FIGS. 1A and 1B . This is beneficial when the patient moves or when the tester needs to position the screener  100  at the proper angle for taking accurate readings. The ear tip  115  also includes a longitudinal throughbore  155 . The throughbore  155  is dimensioned to accept a first end  160  of a microphone housing  165 . The first end  160  of the microphone housing  165  includes a longitudinal cavity  170 . The microphone housing  165  also includes a recess  175  for receiving a microphone  180  therein.  FIG. 2  illustrates an embodiment in which two microphones are used. However, one or more microphones may be used in the present invention. The microphones  180  are held in the recess  175  which is defined by a first shoulder  185  and a second shoulder  190 . The shoulders  185 ,  190  protect the microphones  180  as well as provide a defined volume in which the microphones  180  may be located. The microphone housing  165  also includes a cylindrical second end  195  having a bore  200 . The bore  200  is designed to receive the connection  150  (see  FIG. 1 ) which preferably includes one or more sound tubes  202  (see  FIG. 4A ) and electrical connectors  204  for transmitting electrical signals from the microphones  180 . In addition, the cylindrical second end  195  of the microphone housing  165  includes a circumferential notch  205 . The notch  205  is explained further below with reference to  FIG. 3 . 
     Continuing to the right of  FIG. 2 , the hearing screener  100  also includes a microphone housing support member  210  having a through hole  215  for receiving the second end  195  of the microphone housing  165  therethrough. The support member  210  also includes a curved flange  220 . The flange  220  acts as a shield to prevent debris from entering the various components of the hearing screener  100 . The shielding ability is illustrated in more detail in  FIG. 3 , in which the hearing screener  100  is assembled. 
     In addition, the cylindrical coupling sleeve  160  is shown in  FIG. 2 . The coupling sleeve  160  has a open interior  230 . An L-shaped notch  235  having a cavity  240  is also illustrated. A plurality of o-rings  250  fit within the L-shaped notch  235  and are seated in the cavity  240 . In addition, a retaining cap  255  is provided. The retaining cap  255  slips over the cylindrical second end  195  of the microphone housing  165  as illustrated more fully in  FIG. 3  and captures the o-rings  250  by tabs  260  formed in the retaining cap  255 . 
     Also shown in  FIG. 2  is the isolation body  130  which has a cylindrical bore  270  for receiving the cylindrical coupling sleeve  160  therein. The coupling sleeve  160  is held securely in the isolation body  130  by set screws  275  which are tightened into threaded holes  280  formed in the isolation body  130 . A second set of o-rings  290  is secured to the isolation body  130  by screws  295 . The screws  295  bore into the isolation body  130 . Further, the exploded assembly of  FIG. 2  is illustrated in an assembled state in  FIG. 3 . 
       FIG. 3  illustrates an assembled embodiment of the hearing screener  100  of the present invention wherein like parts are represented by like numerals. As illustrated, when the components are assembled, the first end  160  of the microphone housing  165  fits inside the throughbore  155  of the ear tip  115 . In addition, the microphone housing  165  fits in the through hole  215  of the microphone housing support member  210 . In particular, the second end  195  of the microphone housing  165  passes through the support member  210  and the retaining cap  255  so that the circumferential notch  205  located adjacent the second end  195  of the microphone housing  165  is exposed past the retaining cap  255 . Thus, a retaining clip  300  can be clipped around the second end  195  of the microphone housing  165  and reside within the circumferential notch  205  to secure the testing probe  110  assembly together. 
     As illustrated, the o-rings  250  are secured at one end by the cylindrical coupling sleeve  160  and at the other end by the retaining cap  255 . In particular, one end of each o-ring  250  is held in the cavity  240  of the L-shaped notch  235  of the cylindrical coupling sleeve  160 . Another end of each o-ring is held by tabs  260  of the retaining cap  255 . The second set of o-rings  290  is also illustrated in a connected state in  FIG. 3 . The screws  295  hold one end of the o-ring  290  to the isolation body  130 . In addition, screws  305  secure the other end of the o-rings  290  to the housing  140 . The housing  140  also has a cavity  310  and a mounting surface  315 . The screws are preferably screwed into the mounting surface  315  of the housing  140 . 
       FIG. 3  schematically illustrates further components of the hearing screener  100 . For example, a digital signal processor  330  is built into the housing  140 . Also an LCD display  335  is arranged in the housing to provide measurement data as a display to the user. Further, a printer  340  may be used to print out data obtained during the hearing testing. The printer  340  is preferably a small infrared type printer. Also, an infrared connection  345  between the hearing screener  100  and the printer  400  is provided. Also operator control  350  are provided on the housing  140 . 
       FIG. 3  illustrates the hearing screener  100  in a position in which the longitudinal axes of the components is perpendicular to the housing  140 . The two sets of o-rings  250 ,  290  provide free movement about all axes for the testing probe portion  110  of the screener  100 , as well as the isolation body  130 . However, as  FIGS. 1A and 1B  indicate, the testing probe  110  can be displaced at an angle relative to the isolation body  130 , which in turn can also be displaced at an angle relative to the housing  140 . Such compound angular displacements advantageously provide manipulation of the hearing screener  100  to facilitate easy use of the device. Such manipulation capability is provided by the arrangement of the o-rings  250 ,  290 . Embodiments of the arrangement for the o-rings are illustrated in  FIGS. 4A and 4B . 
     For example,  FIG. 4A  illustrates a cross-section view of the arrangement of o-rings  250  which connect the microphone housing  165  to the coupling sleeve  160  within the isolation body  130 .  FIG. 4A  is taken along section line A-A in  FIG. 3 . As shown, four o-rings  250  are equally distributed between coupling sleeve  160  and the second end  195  of the microphone housing  165 . In this manner, the microphone housing  165  is concentrically suspended within the coupling sleeve  160 . As discussed above, one end of the o-ring  250  is held within the coupling sleeve  160  by being captured within the L-shaped notch  235  and residing in the recess  240 . The other end of the o-ring  250  is captured by the tab  260 , which is part of the retaining cap  255 . Also, the coupling sleeve  160  is maintained within isolation body  130  by the set screws  275 . The set screws  275  are tightened down within the screw holes  280  to secure the sleeve  160  within the isolation body  130 . 
       FIG. 4B  also illustrates the plurality of o-rings  290  distributed between the isolation assembly  130  and the housing  140 .  FIG. 4B  is taken along section line B-B of  FIG. 3 . As illustrated, six o-rings  290  are mounted by screws  295  which attach to the isolation body  130  and screws  305  which attach to the mounting surface  315  of the housing  140 . The isolation body  130  is thus concentrically suspended within the housing  140  by the six o-rings  290 . As illustrated in  FIGS. 4A and 4B , the number of o-rings may be chosen for a particular application. Also, the elasticity of the o-rings may be selected for a particular use and resiliency desired. In a preferred embodiment, o-rings of 70 durometer SHORE A provide a sufficient resiliency and feel. However, the number and elasticity of the o-rings may be chosen depending on the application desired. 
     As set forth above, vibrations caused by the user holding onto the screener apparatus  100  are translated into noise. An advantage of the present invention is a dampening of this noise so that it does not interfere with the measurements being taken.  FIG. 5  graphically illustrates how this elimination of the vibrational noise is accomplished. 
       FIG. 5  is a graph illustrating microphone noise various curves plotted for different measurement situations. The Y axis is dB and the X axis is frequency in kilohertz (kHz). The various curves illustrate experimental data taken as different parts of the hearing screener  100  are held by a tester. For example, curve A illustrates the microphone noise floor with the tester holding the ear tip  115  assembly of the hearing screener  100 . Thus, the first set of o-rings  250  and the second set of o-rings  290  are rendered inoperable. Similarly, curve B illustrates the microphone noise floor when the tester holds the isolation assembly  130  of the hearing tester  100 . In this situation, the first set of o-rings  250  is operable, but the second set of o-rings  290  is not. Finally, curve C illustrates a microphone noise floor curve when the tester holds the hearing screener  100  by the housing  140  as intended during a typical use. Thus, both sets of o-rings  250 ,  290  are operable. 
     As a basic reference, curve D illustrates the microphone noise for a microphone, such as an ER-10C microphone. The ER-10C microphone has the same effective noise floor as an industry standard microphone. Thus,  FIG. 5  illustrates that the isolation effects of the o-rings  250  and  290 , along with the arrangement of the preferred embodiment discussed above, yields a microphone noise floor virtually identical to that of the industry standard microphone when the hearing screener  100  is held by the housing  140  as illustrated in curve C. Curve A illustrates that holding the ear tip assembly  115  of the hearing screener  100  prevents the benefits of the o-rings  250 ,  290  from being exploited. As a result, the noise floor is approximately 15 dB more than that experienced in curve C. 
     Thus, as described above and graphically illustrated in  FIG. 5 , the first set of o-rings  250  isolate movements of the patient which cause noise, and the second set of o-rings  290  isolate hand vibration which causes noise. Together, the reduction in noise is sufficient for allowing the hand-held hearing screener  100  of the preferred embodiment discussed above to be used for taking accurate measurements of otacoustic emissions. 
       FIGS. 6 and 7  illustrate another embodiment of the hearing screener  100  built in accordance with the present invention. The hearing screener  100  includes a housing  140 , an isolation body or assembly  130  and a testing probe  110 . As explained more completely above and below, the isolation body  130  acts as, for example, an elastic coupler that suspends the testing probe  110  from the housing  140 . As discussed above, testing probe  110  includes ear tip  115 . 
     The housing  140  includes a keyboard  351  for entry of commands, and a screen  353  for display of data. The screen  353  may be the same as LCD screen  335  discussed above. The housing  140  also includes a serial port  355  (see  FIG. 7 ) for communication of data to a printer (not shown) or to a suitable docking station (not shown) that may be connected to a printer, for printout of data obtained during the hearing testing. The serial port  355  may also be used to communicate data directly to a personal computer. 
     Referring to  FIG. 7 , testing probe  110  includes a removable probe tip  357 . Probe tip  357  is removed by pressing tabs  359  and  361 . Details regarding probe tip  357  are discussed below with respect to  FIGS. 12A and 12B . 
       FIG. 8  is an exploded view of the hearing screener  100  of  FIGS. 6 and 7 . Testing probe  110  of  FIGS. 6 and 7  is comprised of removable probe tip  357 , seal  363 , retainer  365  and shaft  367 . A port (note shown) of microphone  369  is inserted into shaft  367  and a seal  371  provides an acoustic seal between the microphone  369  and the shaft  367 . Upon assembly, microphone  369  rests adjacent an outer surface  373  of shaft  367  and is retained by an inner surface  375  of retainer  365 . Retainer  365  acts as a fulcrom point for tabs  359  and  361  of removable probe tip  357 . Eartip  115  fits over a nose portion  379  of removable probe  357 . 
     Isolation body or assembly  130  of  FIGS. 6 and 7  is comprised of springs  381  and  383  and cylinder  385 . Springs  381  and  383  may be identical. Isolation body or assembly  130  attaches to housing  140  and testing probe  110  as discussed below. 
       FIGS. 9A ,  9 B and  9 C illustrate mounting of the isolation body or assembly  130  onto the housing  140 .  FIG. 9A  shows housing  140  having a mounting extension  387  protruding therefrom.  FIG. 9B  shows spring  381  mounted on the housing  140  via mating engagement of mounting extension  387  into a recess  389  (see  FIG. 8 ) of spring  381 . Mounting extension  387  includes retaining tabs  382  that releasably lock the spring  381  onto mounting extension  387  of the housing  140 .  FIG. 9C  illustrates the assembly of  FIG. 9B  further mounting cylinder  385  thereon. 
       FIG. 10  illustrates more detail of the mounting of cylinder  385  onto spring  381 . Cylinder  385  includes notches  388  that engage couplers  391  of spring  381 . Spring  381  is preferably made of an elastomer type material. Couplers  391  therefore provide elastic mounting of the cylinder  385  in spring  381 . 
     Cylinder  385  further includes grooves  393  and  395 . Groove  393  of cylinder  385  receives and engages ring  397  of spring  381 , thereby mounting and releasably retaining the cylinder  385  on the spring  381 . 
       FIGS. 11A ,  11 B and  11 C illustrate mounting of the testing probe  110  on the spring  383 . Similar to spring  381  as discussed above, spring  383  includes a recess  399  that matingly engages a mounting extension  401  of shaft  367 . Shaft  367  includes retaining tabs  403  to releasable lock spring  383  onto the mounting extension  401  of shaft  367 . As can be seen in  FIG. 11C , spring  383  includes couplers  405  that engage notches  407  of cylinder  385  (see  FIG. 10 ). Spring  383  further includes ring  409  that engages groove  395  of cylinder  385 , thereby mounting and releasably retaining spring  383  on cylinder  385 . 
     The assembly discussed above with respect to  FIGS. 9-11  provides elastic coupling of the testing probe  110  to the housing  140  while preventing direct contact between the testing probe  110  and the housing  140 . Such a configuration assists in reducing the transmission of vibration from the housing  140  to the testing probe  110 . Isolation assembly  130  further enables movement of the testing probe  110  relative to the housing  140  for ease of manipulation during testing, as described above. In addition, the testing probe  110  may be moved relative to the isolation assembly  130 , and the isolation assembly  130  may be moved relative to the housing  140 , thereby providing further ease of manipulation and vibration dampening. 
     As discussed above with respect to  FIG. 8 , microphone  369  is mounted in testing probe  110 . Microphone  369  is electrically connected to suitable circuitry within the housing  140  via ribbon cable  370 . Upon assembly, ribbon cable  370  extends through shaft  367 , cylinder  385  and mounting extension  387  into the housing  140 . 
       FIGS. 12A and 12B  illustrate additional detail of the removable probe tip  357 . During testing, sound is presented into the ear canal of a subject via nose portion  379  of the removable probe tip  357 , and particularly through channels  411  in nose portion  379 . The sound is generated by speakers contained within the housing  140  and transmitted to the channels  411  via flexible sound tubes (not shown) and via fixed tubes  431  and  433  in the shaft  367 . Upon assembly, the flexible sound tubes connect to the fixed tubes and extend from the shaft  367 , through cylinder  385  and mounting extension  387  into the housing  140 , like the ribbon cable  370  discussed above. 
     Signals from the ear canal are received by microphone  369  via channel  413  in nose portion  379  of removable probe tip  357 . Those signals are transduced by the microphone  369  and transmitted to the housing  140 . 
     Channels  411  and  413  of the nose portion  379  of probe tip  357  often become clogged with earwax or other debris, which results in testing failure. Consequently, it is desirable that probe tip  357  be removable from the shaft  367  for cleaning and/or replacement of the probe tip  357 . As mentioned above, probe tip  357  includes tabs  359  and  361  for removable engagement of the probe tip  357  on the shaft  367 . More particularly, shaft  367  includes protruding members  415  and  417  that engage slots in the tabs  359  and  361 , respectively. The probe tip  357  is removed from the shaft  367  by depressing portions  419  and  421  of tabs  359  and  361 , respectively. 
     Upon assembly, seal  363  is trapped between an inner surface  423  of probe tip  357  and an outer surface  425  of shaft  367 . Seal  363  includes openings  427  and  429  that acoustically couple the channels  411  and  413  respectively, to tubes  431  and  433  in shaft  367 . Seal  363  also provides an acoustic seal between the surfaces  423  and  425 . Seal  363  may, for example, be made of an elastomer type material to conform to the surfaces  423  and  425 . 
     While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications as incorporate those features which come within the spirit and scope of the invention.