Patent Publication Number: US-11043229-B2

Title: System and method for drowning detection

Description:
FIELD OF THE INVENTION 
     The present invention relates to a system and method for the detection of drowning within a body of water, and in particular, to such a system wherein the detection is provided by processor implemented signal processing of acoustic signals from within the body of water. 
     BACKGROUND OF THE INVENTION 
     Drowning can occur in any body of water or the like environments such as a pool, lake, sea, ocean and even a bathtub. Drowning does not necessitate that the person does not know how to swim, other factors may come into play that lead to drowning, such as head trauma, orientation loss, disorientation and loss of consciousness. 
     Children of ages 2-9 are the high risk group for fatal drowning. Daily drowning statistics in the USA show that there are about 160 drowning incidents of which 120 receive first aid, 40 are hospitalized; 15 recover, 15 suffer irreversible damage and 10 are fatal cases. 
     Various forms of floatation devices and detections devices exist that function based on individual wearing protective gear such as life vests, floaties, swim rings, variously shaped inflatable floatation devices. 
     U.S. Patent Publication No. 2013/0328683 to Sitbon et al, teaches a wearable device for drowning detection based on signal processing specific of a an individual wearing the device. 
     U.S. Pat. No. 6,111,510 to Coffelt, discloses a system for underwater drowning detection system that is based on the presence and absence of a sound wave of a bodily function. 
     SUMMARY OF THE INVENTION 
     There is an unmet need for, and it would be highly useful to have a system and method capable of identifying a drowning incident occurring within a body of water while identifying and communicating the location of the drowning victim. Preferably the location of the individual is communicated to emergency respondents such as lifeguards, medical practitioners, or the like individuals and/or automated devices capable of treating or responding to such emergency events. 
     Embodiments of the present invention provide for detection of drowning incident by utilizing a system configured to monitor a body of water while listening for and detect an acoustic signature that is correlated with drowning. In embodiments, when such a drowning acoustic signature is detected an alarm state protocol is implemented. The alarm state preferably includes at least one of sounding and alarm, alerting competent first respondents, alerting emergency services, the like or any combination thereof. 
     In embodiments they system further provides for identifying the location of the drowning victim by identifying the location of the source of the acoustic signature. 
     In embodiments the system comprises an array of hydrophones that are submerged within a body of water that is being monitored. The hydrophone array is functionally linked to a processing device for performing digital signal processing and analysis of the acoustic signal provided by the hydrophone array. In embodiments the signal processing and analysis provide for detecting an acoustic signature indicative of drowning. 
     In embodiments the system may further comprise additional sensors that may be utilized to improve signal to noise ratio. For example a microphone may be placed external the body of water to determine background noise. For example, in a pool setting a microphone may be placed near the pool&#39;s water-pump and filter providing additional data of the surrounding noise. 
     In embodiments the system may further comprise additional submersible and/or under water sensors to improve signal to noise ratio from noise emanating from within the body of water being monitored. Such an underwater sensor module may comprises sensors for example including but not limited to movement sensor, accelerometer, gyro sensor, depth sensor, pressure sensor, temperature sensor, pH sensor, camera, optical sensor, the like, or any combination thereof configured to be submersible within the monitored body of water. 
     In embodiments the system may further be in communication with or functionally associated with at least one or more auxiliary devices for communicating an alarm state and/or sounding an alarm state. An auxiliary device may for example include but is not limited to a horn, an alarm, a communication device, a mobile communication device, a server, a first respondent call center, emergency services call center, the like or any combination thereof. 
     The system and method of the present invention preferably provides a safety measure against accidental drowning within an aqueous environment such as a pool, lake, ocean or the like body of water. 
     In embodiments the hydrophone array comprising a plurality of hydrophones may be distributed and/or arranged within the monitored body of water in any manner so as to provide sufficient coverage of the entire area of the body of water. For example the hydrophone array may be arranged in a grid arrangement, a concentric arrangement, a triangulation arrangement, single layer arrangement, multi-layered (depth) arrangement, the like or any combination thereof. 
     In some embodiments the hydrophone array may be arranged in a planar grid-like manner along a lower surface of the body of water, for example a swimming pool. 
     In some embodiments the hydrophone array may be arranged in multilayer arrangement wherein hydrophones are placed along a lower surface and along at least one or more side (wall) surface. For example, a first hydrophone array arrangement along the bottom surface of a pool and a second hydrophone array arrangement along the height of at least one or more walls of a pool. 
     In embodiments the hydrophones may be placed at a distance (d) from the walls and/or edges of a pool defining the body of water being monitored. distance d confirmed so as to ensure the quality of the acoustic signal bine monitored ad so as to reduce and/or circumvent any echo and/or reflection effect that may arise by placement of hydrophone along the edge of the body of water for example a pool wall. 
     In embodiments placement of each hydrophone is preferably provided with a unique location specific address for example a GPS address and/or coordinates. Preferably the unique hydrophone address is provided to facilitate identification and localization of the source of the drowning event within the body of water and to further provide for communicating the location of a drowning victim within the body of water. Optionally location is communicated to an auxiliary device and/or system as previously described and identifiable on a map. 
     In embodiments, individual hydrophones forming the hydrophone array may be further associated with a local sensor and/or transducer, for example including but not limited to a pH sensor and/or a temperature sensor, a light source, accelerometer, the like or any combination thereof. More preferably individual hydrophones may be associated with and/or adjacent to a temperature sensor to determine the ambient water temperature. In some embodiments a selective portion of the hydrophones array will be fit and/or functionally associated with a temperature sensor. 
     In embodiments the hydrophone array may be formed from a plurality of individual hydrophones that are functionally coupled with the processing center and/or device in a wired or wireless manner. Accordingly the hydrophones may be wireless and/or wired hydrophones that are functionally coupled and operational with the processing center and/or device. 
     In embodiments the processing center provides for implementing a proprietary processor mediated signal processing method of the acoustic signals received from the hydrophone array in order to monitor, detect and locate a drowning incident within a body of water. 
     In embodiments the processor mediated signal processing method comprises performing filtering and analysis in the frequency domain to identify a unique acoustic signature indicative of a drowning individual. The acoustic signature is identifiable and within a specific frequency band from about 200 Hz up to about 1200 Hz. 
     In embodiments, the processing center preferably comprises and/or is functionally associated with an acoustic signature bank and/or library and/or database of a pre-classified drowning acoustic signature signals that will preferably facilitate the process of the identification and analysis of the acoustic signals obtained from the hydrophone array. 
     Most preferably the acoustic signature is associated with acoustic waves generated by a drowning individual during a drowning event. The drowning sound may be explained on the basis of known anatomical defense reflexes that together are implemented to try to prevent entry of water or unwanted substance into the upper and lower respiratory system. These reflexes include a laryngospasm and a cough reflex that are known to be activated by irritant receptors that are located mainly on the wall of the trachea, pharynx, and carina, or by stimulation of the auricular branch (Arnold&#39;s reflex via internal laryngeal nerve). When both reflexes are triggered, axonal impulses of the vagus nerve begin a chain reaction that reaches the medulla, with efferent back in to respiratory system (glottis, vocal cords, diaphragm, intercostal muscles) is observed. A combination of these reflexes activate a blocking and/or repelling defensive actions to prevent water, or the like foreign object, from entering the respiratory system, and in turn gives rise to the unique drowning acoustic signature, monitored by the system and method defining embodiments of the present invention. 
     In embodiments, the processing center provides for identifying the location of the drowning incident by processing digital data received from the hydrophone array by utilizing a phase control processing techniques to generate a directional beam emanating from select hydrophones so as to determine and map the location of the drowning incident relative to the hydrophone array placement. 
     Within the context of this application the term hydrophone refers to an underwater microphone adept at obtaining acoustic signals under water. Any form of a hydrophone as is known in the art may be utilized. 
     It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims. 
     Citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the invention. 
     Section headings are used herein to ease understanding of the specification and should not be construed as necessarily limiting. 
     Unless otherwise defined the various embodiment of the present invention may be provided to an end user in a plurality of formats, platforms, and may be outputted to at least one of a computer readable memory, a computer display device, a printout, a computer on a network or a user. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting. 
     Implementation of the method and system of the present invention involves performing or completing certain selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of preferred embodiments of the method and system of the present invention, several selected steps could be implemented by hardware or by software on any operating system of any firmware or a combination thereof. For example, as hardware, selected steps of the invention could be implemented as a chip or a circuit. As software, selected steps of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions. 
     It should be noted that optionally any device featuring a data processor and/or the ability to execute one or more instructions may be described as a computer, including but not limited to a PC (personal computer), a server, a minicomputer, a cellular telephone, a smart phone, a PDA (personal data assistant), a pager, or the like. Any two or more of such devices in communication with each other, and/or any computer in communication with any other computer may optionally comprise a “computer network”. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in order to provide what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
       In the drawings: 
         FIG. 1  is a schematic block diagram of a system for drowning detections according to an embodiment of the present invention; 
         FIG. 2  is a schematic flow chart showing a method for identifying a drowning incident with the system according to the present invention; 
         FIG. 3  is a schematic illustration of a swimming pool fit with the system for drowning detection according to an embodiment of the present invention; 
         FIG. 4  is a schematic block diagram of a system and method implementation for drowning detections according to an embodiment of the present invention. 
         FIG. 5A-B  are schematic graphical illustrations of and acoustic signal obtained with the system according to an embodiment of the present invention; 
         FIG. 5A  shows filtered raw signals, in the time domain, obtained from the hydrophone array;  FIG. 5B  shows the signal in the frequency domain following signal processing that identifies a drowning acoustic signature in the range between 200 Hz and 1200 Hz. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The principles and operation of the present invention may be better understood with reference to the drawings and the accompanying description. 
     The following figure reference labels are used throughout the description to refer to similarly functioning components are used throughout the specification hereinbelow.
           10  monitored body of water;     12  pool systems;     20  auxiliary device;     100  monitoring system;     102  hydrophone array;     104  processing center;     105  alarm signal;     106  external environmental sensor;     108  in-water auxiliary sensor module;     110  signal processing module;     112  adaptive filter;     114  frame splitter;     116  frequency analysis;     118  signature library;     120  beam forming phase control module;     122  decision logic module;     124  alarm state module;     130  electronics/circuitry module;     132  microprocessor sub-module;     134  power sub-module;     136  communication sub-module;     138  memory sub-module;       

     Referring now to the drawings,  FIG. 1  is a schematic block diagram of system  100  provided for monitoring a body of water for a drowning event, by implementing a processor mediated signal processing method for detecting a drowning event and altering of the same. 
     System  100  comprises a hydrophone array  102  including a plurality of hydrophones ( 102   a . . . n ) including ‘n’ hydrophones where ‘n’ is at least four (n&gt;4) that are submerged in the body of water being monitored, and a processing center  104  that provides processor mediated signal processing of the acoustic signals provided by the hydrophone array  102  so as to detect the drowning event. 
     In embodiments the hydrophone array  102  may take any form where the plurality of hydrophones may be distributed and/or arranged within the monitored body of water in any manner so as to provide sufficient coverage of the entire area of the body of water that is to be monitored. 
     For example the hydrophone array  102  may be arranged in a grid arrangement, a concentric arrangement, a triangulation arrangement, single layer arrangement, multi-layered (depth) arrangement, the like or any combination thereof. 
     In some embodiments the hydrophone array  102  may be arranged in a planar grid-like manner along and/or adjacent to a lower surface of the body of water, for example a swimming pool. For example in a non-limiting embodiment array  102  may be disposed along the swimming pool floor. For example, in a non-limiting embodiment array  102  may be disposed adjacent to a swimming pool floor and/or wall wherein individual hydrophones forming array  102  may be placed at a distance (d) above the swimming pool floor itself such that the hydrophones are suspended near the floor but not on the floor itself. In some embodiments distance (d) may be in the order of a few centimeters for example up to about 15 cm from the swimming pool floor. 
     In some embodiments the hydrophone array may be arranged in multilayer arrangement wherein hydrophones are placed along a lower surface and along at least one or more side (wall) surface. For example, a first hydrophone array arrangement may be placed along the bottom surface of a pool and a second hydrophone array arrangement along the height of at least one or more walls of a pool. 
     For example, a hydrophone array  102  disposed within a swimming pool may comprise at least four hydrophones  102   n , that are organized in a grid-like manner, and distributed in two rows, wherein each row is disposed on the pool&#39;s floor and near the pool&#39;s wall, that is along opposite junctions of the pool&#39;s long edge. A first row disposed adjacent to the bottom of the left pool wall and a second row of hydrophones disposed opposite the first row, and placed adjacent to the bottom of the right pool wall. 
     For example in a non-limiting embodiment array  102  may be disposed along the swimming pool floor and/or side walls wherein individual hydrophones forming array  102  may be placed at a distance (d) from the wall and/or floor of the swimming pool such that the hydrophones are suspended near the floor and/or wall. In some embodiments distance (d) may be in the order of a few centimeters for example up to about 15 cm from the swimming pool wall and/or floor. 
     In embodiments the number of individual hydrophones  102   n  will be a function of the pool&#39;s dimensions. For example, a hydrophone may be placed at set intervals of about 1 meter and up to about 3 meters along the pool&#39;s length. 
     In embodiments placement of each hydrophone is preferably provided with a unique location specific address for example a GPS address and/or geographical coordinates. Preferably the unique hydrophone address is provided to facilitate communicating the location of a drowning incident and/or victim within the body of water. Optionally the location is communicated to an auxiliary device  20  and/or system and wherein the location is identifiable on a map. 
     In some embodiments system  100  may optionally further comprise a non-aqueous sensor module  106 . Sensor module  106  provides for improving the signal to noise ratio of the acoustic signals picked up by the hydrophone array  102 . Sensor module  106  may comprise at least one or more microphone that are placed external the body of water to determine background noise sensed within the body of water. 
     For example, in an optional system  100  that is utilized in a pool setting, a microphone  106  may be placed adjacent to the pool&#39;s machine room to pick up acoustic signal emanating from the pool&#39;s water-pumps and filters providing so as to identify their contribution to noise and/or acoustic signals sensed by the hydrophone within the body of water. Such data may be utilized by system  100  to improve signal to noise ratio by provide additional data of potential environmental noise in and around the body of water. A further example, an external microphone may be placed to monitor above ground sounds in the perimeter of the body of water, for example a swimming pool, to improve signal to noise ratio where noise generated above the water surface may be removed and/or accounted for when monitoring and/or listing for an in water drowning acoustic signature signal. For example, noise generated by kids splashing and playing above the water surface that is received and/or picked up by the underwater hydrophone array  102  may be filtered out and/or accounted for and/or recognized as noise, so as to improve signal to noise ratio of the hydrophone signal. 
     In some embodiments system  100  may be further fit with an auxiliary in-water sensor module  108 , including at least one or more submerged and/or underwater sensors and/or transducer to facilitate and/or improve the hydrophone signal. Such additional submersible and/or under water sensors  108  is provided to improve signal to noise ratio from noise emanating from within the body of water being monitored. Such an underwater sensor module  108  may comprise sensors for example including but not limited to movement sensor, accelerometer, gyro sensor, depth sensor, pressure sensor, temperature sensor, pH sensor, camera, optical sensor, light the like, or any combination thereof configured to be submersible within the monitored body of water. 
     Processing center  104  is a processing and communication device that provides for undertaking the communication and signal processing required to identify an acoustic drowning signature signal obtained with hydrophone array  102 . Processing center  104  implements a processor mediated method ( FIG. 2 ) for identifying the acoustic drowning signature signal. 
     In embodiments processing center  104  may disposed within the body of water and/or external to the body of water being monitored. In some embodiments processing center may be formed from a plurality of sub-modules wherein a some sub-modules are within the body of water and some sub-modules are external to the body of water. 
     In embodiments processing center  104  may be functionally associated with the hydrophone array in a wired or wireless manner. Accordingly the hydrophone array  102  may be wireless hydrophones and/or wired hydrophones that are functionally coupled and operational with the processing center and/or device  104 . 
     Processing center  104  comprises a signal processing module  110  and an electronics/circuitry module  130  that provide for identifying an acoustic drowning signature signal within the body of water and implementing an alarm procedure and/or state once the drowning incident is identified and including generating and communicating an alarm signal  105 . 
     Signal processing module  110  preferably provides for implementing the processor mediated method for identifying the acoustic drowning signature signal form the acoustic signals provided by hydrophone array  102 , greater detail provided in  FIG. 4 . 
     Electronics/circuitry module  130  preferably provides the hardware and/or software necessary to implement the processing and communication necessary to monitor the body of water to identify a drowning acoustic signature. 
     Electronics/circuitry module  130  comprises a microprocessor sub-module  132 , a power sub-module  134 , a communication sub-module  136 , a memory sub-module  138 , the like or any combination thereof. 
     In embodiments processor sub-module  132  provides the necessary processing hardware and/or software necessary to render processing center  104  functional and/or to render system  100  functional. 
     In embodiments power sub-module  134  provides the necessary hardware and/or software to power processing center  104  and/or system  100 . 
     In embodiments communication sub-module  136  provides the necessary hardware and/or software to facilitate communication for system  100  with auxiliary devices  20  and/or the hydrophone array  102 . 
     In embodiments memory sub-module  138  provides the necessary hardware and/or software to facilitate operations of system  100  and/or processing center  104 . 
     In embodiments system  100  is preferably in communication with or functionally associated with at least one or more auxiliary devices  20  for communicating an alarm signal  105  indicative of an alarm state and/or sounding an alarm state. 
     An auxiliary device  20  may for example include but is not limited to a horn, an alarm, a communication device, a mobile communication device, a server, a first respondent call center, emergency services call center, the like or any combination thereof. Optionally, an auxiliary device  20 , for example a mobile communication device such as a smartphone, may be fit with necessary software and/or dedicated application (app) to receive an alarm state signal  105 . 
     In some embodiments system, the hydrophone array  102  may be formed from a plurality of sub-arrays that are associated with processing center  104 . For example to cover a large body of water a plurality of sub-arrays may be utilized with a single processing center  104 . 
     In embodiments a hydrophone array and/or sub-array may be embedded in a flexible platform and/or housing that maintains the arrangement of the individual hydrophone forming the array and/or sub-array. For example, such a housing and/or flexible platform may be a vinyl surface that is embedded with individual hydrophones and submerged within the body of water being monitored. 
     In embodiments, the flexible platform and/or housing may be functionally coupled with processing center  104  by wiring or wireless communication. 
     In embodiments, the housing and/or platform of the hydrophone array  102  and/or sub-array may further comprise a local electronics and circuitry module comprising a power source sub-module, processor sub-module, memory sub-module, and communication sub-module, and wherein the local electronics and circuitry module is functionally coupled with the processing center  104  by way of a wireless communication protocol and/or hard wiring. 
     In embodiments the platform and/or housing may be a flexible water impermeable material, for example including but not limited to vinyl. 
     In embodiments, individual hydrophones ( 102   n ) forming the hydrophone array  102  may be further associated with a local sensor and/or transducer, for example including but not limited to a light source, a pH sensor, a temperature sensor, and/or an accelerometer, the like or any combination thereof. 
     In embodiments individual hydrophones ( 102   n ) may be fit with a temperature sensor to determine the temperature in and around the individual hydrophone ( 102   n ) and the hydrophone array ( 102 ). In particular, such a temperature sensor could facilitate signal processing of the sound recorded with the hydrophones. 
     In embodiments individual hydrophones ( 102   n ) may be fit with an accelerometer to aid in signal processing, and in particular to improve on signal to noise ratio of the acoustic signal provided by array  102  and/or individual hydrophones  102   n.    
     In embodiments individual hydrophones  102   n  may be fit with and or disposed adjacent to a light source, for example a Light Emitting Diode (LED). In embodiments, the LED adjacent to a hydrophone  102   n  may be a multi-color (RGB) LED. In embodiments system  100  may be configured to activate the light source selectively only if a drowning incident is sensed. In embodiments, only the lights adjacent to the location of the drowning event are activated so as to readily identify the location of the drowning incident. 
     In embodiments, the wavelength of the light source may be selected and/or lit according to its proximity to the drowning event, therein acting to facilitate as a locating and/or honing signal to identify the location of the drowning event, in particular such is advantageous at night or dark environment. For example, light closest to the drowning event/location may be selectively lit as Red while those light that are further away from the drowning event/location may be lit as Blue. 
       FIG. 2  shows a flow chart of a method for identifying a drowning event by way of identifying an drowning acoustic signature within a body of water, for example a swimming pool, that is fit with and monitored with system  100 . 
     First in stage  200 , real time acoustic signals are received from the hydrophone array  102  disposed within the body of water being monitored. The acoustic data is communicated to and delivered to processing center  104  for processing substantially in real time. 
     Next in an optional stage  201 , the raw data obtained undergoes beam forming via a phase control module  120  where each hydrophone  102   n  comprising the hydrophone array  102  is utilized to form a plurality of directional acoustic beams in a manner that will cover the area defined by the hydrophone array  102  and the volume of the body of water being monitored. Preferably beam forming facilitates locating the drowning event as will be described below in optional stage  205 . In embodiments the phase control module  120  will apply variable phase control shifts to individual hydrophones ( 102   n ) of the hydrophone array  102  so as to cover the entire monitored body of water. 
     Next in stage  202 , processing center  104  and more preferably signal processing module  110  applies noise reduction filtering so as to clean the hydrophone acoustic signal allowing further processing of the signal. Preferably the filter applied may be applied directly to the data provided by array  102  as well as additional environmental data provided from external sensor module  106 . Filtering may for example include adaptive filtering or the like filtering as is known in the art. 
     Next in stage  204 , further signal processing techniques are implemented on the clean signal to identify the drowning acoustic signal within the body of water and an alarm signal  105  is generated. Preferably such signal processing techniques comprise filtering, frame splitting, frequency domain analysis, artificial intelligence decision support analysis, signal decimation, down sampling, up sampling, interpolation, determination of minimum and/or maximums, identifying harmonics, wavelet analysis, power analysis, signal differentiation, signal compression, signal decompression, transformations, regression analysis, or the like as is known in the art. 
     Next in optional stage  205 , if a drowning acoustic signature signal is identified, the processing module further identifies the location of the individual hydrophones ( 102   n ) that generated and/or picked up and/or are involved in the identification of the drowning signature signal, so as to identify the location of the suspect drowning event. Optionally and preferably during an alarm state preferably the drowning incident location is identified and communicated. 
     In embodiments, determining the location of the suspect drowning event may comprise: providing individual hydrophones ( 102   n ) with an address in the form of a geographical coordinates (GPS coordinates), preferably an address is provided during installation of system  100 ; next determine from the acoustic data which of the hydrophones are involved in generating the acoustic drowning signature signal; finally, cross reference the hydrophones involved in generating the signature signal with the hydrophone&#39;s geographical coordinate address to define area of drowning event. 
     Next in stage  206 , alarm state signal  105  is communicated to at least one or more auxiliary device  20  associated with system  100 , to undertake an alarm state protocol. Optionally and preferably an alarm state signal  105  may further comprise the location of the drowning event based on location identified in optional stage  205 . Preferably the location is provided in the form of geographical coordinates. 
       FIG. 3  shows a schematic illustration of system  100  as implemented in an in-ground swimming pool  10  setting. As seen hydrophone array  102  comprises a plurality of individually hydrophones  102   a ,  102   b ,  102   n  is disposed along a lower surface of the pool, forming a grid-like coverage of the pool floor. Array  102  is functionally linked and/or associated with processing center  104  shown as being above ground. 
     System  100 , shows pool systems and/or machine rooms  12 , comprising filter and pumps, that are fit with an optional sensor  106  that is functionally coupled with processing center  104 . Preferably processing center  104  can apply adaptive filters to data received from sensor  106  so as to improve the signal to noise ratio received form array  102 . 
     As shown, system  100  and in particular processing center  104  is further functionally associated with an auxiliary device  20  for receiving an alarm state signal  105  that may be communicated from processing center  104 . 
     While  FIG. 3  depicts implementation of system  100  with a built-in swimming pool  10 , system  100  is not limited to such implementation and may be utilized in any body of water having a defined and/or definable monitoring area. Such a body of water may for example include but is not limited to at least one or more of an above ground swimming pool, a defined area within a lake, a defined area within a body of water, a defined area within an ocean, a defined area within a sea, a water reservoir, a water tank, an artificial lake, a canal, a bathtub, a Jacuzzi or the like. 
       FIG. 4  show a further depiction of system  100  showing processing module  110  in greater detail. As shown, acoustic signals from at least one of array  102  and/or sensor  106  are provided to and/or communicated to processing center  104 . 
     In embodiments, the raw acoustic signals from array  102  are communicated to a beam forming phase control module  120  generating directional data set from the hydrophone data provided by array  102 . 
     In embodiments module  120  is utilized to form a plurality of directional acoustic beams in a manner that will cover the area defined by the hydrophone array  102  and the volume of the body of water being monitored. Preferably such beam forming facilitates locating the drowning event relative to the location of the hydrophones. 
     In embodiments the phase control module  120  will apply variable phase control shifts to individual hydrophones ( 102   n ) of the hydrophone array  102  so as to form beams that will cover the entire monitored body of water. 
     Preferably the acoustic directional data set and the external sensor data  106  is communicated to signal processing module  110  to undertake and perform data filtering with an adaptive filter module  112 , frame splitting with frame splitting module  114 , and to perform frequency analysis with frequency analysis module  116 . All provided to identify an acoustic signature signal that is associated with a drowning event. More preferably the acoustic signature has an identifiable frequency band from about 200 Hz and up to about 1200 Hz and optionally up to about 1500 Hz. 
     The processed data is then provided to decision logic module  122  and/or automated classifier provided that facilitate identifying and/or classifying the signal into a drowning signal or not. Preferably the decision module  122  is rendered with reference to a bank and/or library and/or database  118  comprising a plurality of pre-classified drowning signatures and/or drowning signal criteria. In some embodiments, module  122  may further be provided with artificial intelligence and learning capabilities and able to identify and learn drowning incident over time. 
     If module  122  positively identifies a drowning incident an alarm state protocol module  124  is implemented. Preferably module  124  generates alarm signal  105  and communicates it to the appropriate auxiliary devices  20 , as previously described. More preferably module  124  further communicates the location of the drowning event relative to the location of the hydrophone nearest the drowning incident. 
       FIG. 5A  shows an example of a time domain acoustic signal of a drowning incident as provided by a hydrophone array  102  prior to classification however following adaptive filtering. The signal shown in  FIG. 5A  does not implicitly show specific signals that are identifiable with a drowning incident, therefore a signature is not readily identifiable from the time domain signal. 
       FIG. 5B  shows the signal depicted in  FIG. 5A , following frequency domain processing where an acoustic signature associated with drowning is visible with frequency bands that are identifiable in the 200 Hz to 1500 Hz. 
     This acoustic signature is believed to be associated with acoustic waves generated by the body during a drowning event. The drowning sound may be explained on the basis of known anatomical defense reflexes that together are implemented to try to prevent entry of water or unwanted substance into the upper and lower respiratory system. These reflexes include a laryngospasm and a cough reflex that are known to be activated by irritant receptors that are located mainly on the wall of the trachea, pharynx, and carina, or by stimulation of the auricular branch (Arnold&#39;s reflex via internal laryngeal nerve). When both reflexes are triggered, axonal impulses of the vagus nerve begin a chain reaction that reaches the medulla, with efferent back in to respiratory system (glottis, vocal cords, diaphragm, intercostal muscles) is observed. A combination of these reflexes activates a blocking and/or repelling defensive actions to prevent water, or the like foreign object, from entering the respiratory system, and in turn gives rise to the unique drowning acoustic signature, monitored by embodiments of the present invention. 
     While the invention has been described with respect to a limited number of embodiment, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. 
     Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not described to limit the invention to the exact construction and operation shown and described and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 
     Having described a specific preferred embodiment of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to that precise embodiment and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope or spirit of the invention defined by the appended claims. 
     Further modifications of the invention will also occur to persons skilled in the art and all such are deemed to fall within the spirit and scope of the invention as defined by the appended claims. 
     While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.