Patent Publication Number: US-2022212020-A1

Title: Variable sound system for audio devices

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/061,556, filed Oct. 1, 2020, which is a continuation of U.S. patent application Ser. No. 16/576,246, filed Sep. 19, 2019, now U.S. Pat. No. 10,792,507 issued Oct. 6, 2020, which is a continuation of U.S. patent application Ser. No. 16/267,182, filed Feb. 4, 2019, now U.S. Pat. No. 10,441,806 issued Oct. 15, 2019, which is a continuation of U.S. patent application Ser. No. 15/617,862, filed Jun. 8, 2017, now U.S. Pat. No. 10,195,452, issued on Feb. 5, 2019, which is a continuation of U.S. patent application Ser. No. 14/526,108, filed Oct. 28, 2014, now U.S. Pat. No. 9,713,728 issued Jul. 25, 2017, which claims the benefit of and priority to U.S. Provisional Patent Application No. 61/897,136, filed Oct. 29, 2013, and titled “Variable Sound System for Medical Devices,” each of which is incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The disclosed subject matter pertains to the area of electronic devices. 
     BACKGROUND INFORMATION 
     The use of field-deployed medical devices, such as portable defibrillators, is achieving widespread acceptance. Such devices are designed to be used in high-stress environments by people who may not be well trained. Thus, the medical devices commonly provide audible cues to the user to guide the use of the medical device. However, such medical devices may be deployed in greatly disparate noise environments ranging from very quiet, such as an office setting, to very loud, such as a railroad station. Thus, the audible cues must compete with drastically different ambient sounds that interfere with the intelligibility of the audible cues. 
     Portable devices are also constrained by size, weight, and power limitations. 
     Summary of Embodiments 
     Disclosed is a system capable of self-adjusting both sound level and spectral content to improve audibility and intelligibility of medical device audible cues. Audible cues are stored as sound files. Ambient noise is detected, and the output of the audible cues is altered based on the ambient noise. Various embodiments include processed sound files that are more robust in noisy environments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a scene where an external defibrillator is used to save the life of a person. 
         FIG. 2  is a functional block diagram generally illustrating core components of one basic embodiment. 
         FIG. 3  is a functional block diagram illustrating components of a first alternative embodiment that improves on the basic embodiment of  FIG. 1   
         FIG. 4  is a functional block diagram illustrating components of a second alternative embodiment that improves on the first alternative embodiment of  FIG. 3 . 
         FIG. 5  a functional block diagram illustrating components of a third alternative embodiment that improves on the first and second alternative embodiments of  FIGS. 3 and 4 . 
         FIG. 6  is a sample spectrogram illustrating a 440 Hz pure sine tone, representing an audible cue. 
         FIG. 7  is a spectrogram illustrating a 400 Hz masker signal. 
         FIG. 8  is a sample spectrogram revealing that when presented together, the 400 Hz masking sound dominates the 440 Hz audible cue. 
         FIG. 9  is a sample spectrogram showing an audible cue processed to include harmonics of the audible cue. 
         FIG. 10  is a sample spectrogram showing the altered audible cue of  FIG. 9  in combination with the masker signal shown in  FIG. 8 . 
         FIG. 11  is a sample spectrogram showing the altered audible cue of  FIG. 9  in combination with a masker signal having harmonics. 
         FIG. 12  is a sample spectrogram illustrating an audible cue altered in accordance with characteristics of the human auditory system. 
         FIG. 13  is a sample spectrogram illustrating the critical band (described below) altered audible cue of  FIG. 12  combined with the masking signal of  FIG. 8 . 
         FIG. 14  is a sample spectrogram illustrating the critical band altered audible cue of  FIG. 12  combined with the masking signal having harmonics. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Generally described, embodiments are directed at discovering information about an ambient sound environment, such as sound level, or spectral content or both, and exploiting psycho-acoustic principles of the human auditory system to enhance the ability to distinguish intended audible cues from ambient noise. Specific embodiments exploit masking and critical bands in the basilar membrane. Combining a measurement of the ambient sound environment and a psycho-acoustically driven knowledge base of the spectrum, a sound source is chosen or modified as necessary to improve resistance to auditory masking, thereby improving the audibility of alerts and alarms, and intelligibility of voice prompts. Although particularly applicable to the area of portable medical devices, the disclosed subject matter has applicability to many other areas, such as the automotive industry, or the like. 
       FIG. 1  is a diagram of a defibrillation scene. A person  82  is lying supine. Person  82  could be a patient in a hospital, or someone found unconscious and turned on his or her back. Person  82  is experiencing a condition in their heart  85 , which could be Ventricular Fibrillation (VF). 
     A portable external defibrillator  100  has been brought close to person  82 . At least two defibrillation electrodes  104 ,  108  are usually provided with external defibrillator  100 . Electrodes  104 ,  108  are coupled with external defibrillator  100  via respective electrode leads  105 ,  109 . A rescuer (not shown) has attached electrodes  104 ,  108  to the skin of person  82 . Defibrillator  100  is administering, via electrodes  104 ,  108 , a brief, strong electric pulse  111  through the body of person  82 . Pulse  111 , also known as a defibrillation shock, goes also through heart  85 , in an attempt to restart it, for saving the life of person  82 . Defibrillator  100  can be one of different types, each with different sets of features and capabilities. The set of capabilities of defibrillator  100  is determined by planning who would use it, and what training they would be likely to have. 
     In use, defibrillator  100  provides audible cues to inform the rescuer of the steps to properly operate defibrillator  100 . However, the defibrillation scene may occur in any one of many different environments having greatly divergent audible characteristics. In other words, the defibrillation scene may occur in a relatively quiet indoor environment, or it may occur in a relatively loud outdoor environment, or anything in between. Operating in various noise environments poses problems for selecting the appropriate format to output the audible cues. In loud environment the audible cues can be difficult to hear if too quiet. In quiet environments, the audible cues can be harsh on the ear and even quasi painful if too loud. Either case (quiet or loud environments) both result in degradation in speech intelligibility under the foregoing conditions. Disclosed are embodiments that enable the defibrillator  100  to automatically adjust the sound output of the audible cues based on the ambient noise environment. 
     Generally stated, when two sounds are closely related in time and frequency such that they are within a critical band of each other, the sound with the lower sound level will be masked by the one with the higher sound level. This phenomenon is illustrated with reference to the sample spectrograms of  FIGS. 6-8 . In the spectrograms, the “X” axis denotes time; 0 to 10 seconds. The “Y” axis represents frequency; 0 to 4000 Hz. Sound levels are represented by brightness on the spectrogram; brighter is higher sound level, darker is lower sound level. For simplicity of discussion, simple sounds will be presented. However, the concepts extend equally to complex sounds including music and speech. 
     Referring briefly to  FIG. 6 , illustrated is a sample spectrogram showing a 440 Hz pure sine tone. This tone represents an audible cue (e.g., an alert) to be communicated to a user of a medical device.  FIG. 7  is a spectrogram illustrating a 400 Hz masker signal. The masker signal will be the interfering ambient sound.  FIG. 8  is a sample spectrogram revealing that when presented together, the 400 Hz masking sound dominates the 440 Hz audible cue. In this situation the 440 Hz audible cue will not be audible over the masker signal. The embodiments shown in  FIGS. 2   5  seek to ameliorate this situation and enhance intelligibility of audible cues output by a medical device. 
       FIG. 2  is a functional block diagram generally illustrating components of one basic embodiment. In this basic embodiment, a system  200  is implemented in a medical device and includes a microphone  202  to record the ambient noise being experienced in the environment and a library  201  of sound files which each represent audible cues. Each audible cue may be, in one implementation, a voice prompt or instruction for operating the medical device. In accordance with this embodiment, each sound file is processed to enhance intelligibility in loud environments. More specifically, the sound files may be processed to enhance harmonic signals of each audible cue, which serves to enhance the intelligibility of the audible cue, especially in louder environments. However, such processing may result in an audible cue which sounds somewhat harsh in quiet environments. Thus, it is desirable to output the audible cues at a volume that does not irritate the operator&#39;s hearing. Illustrative processing methods are illustrated in  FIGS. 9-14  and described below. 
     The sound recorded using the microphone  202  is conditioned using signal conditioner  204  and converted from an analog signal to a digital signal using ADC  206 . A sound level calculation component  208  then detects the sound level (e.g, volume) of the noise in the ambient environment. Using the detected sound level, a gain adjustment is applied to an amplifier  212  thus adjusting the sound level of audible cues such that it is appropriate for the current environment. 
     In various implementations, the gain adjustment  210  could be either an analog or digital control, with the latter depicted in  FIG. 2 . While offering intelligent adjustment of the sound level, this version offers basic improvement in resistance to auditory masking by ambient sounds. 
       FIG. 3  is a functional block diagram illustrating components of a first alternative embodiment  300  that improves on the basic embodiment of  FIG. 1 . Generally stated, components shown in  FIG. 3  operate in the same manner as similarly-labeled components shown in  FIG. 2 . However, the sound files in the sound library  301  of the first alternative embodiment are somewhat less processed than those in the sound library  201  of the basic embodiment. Accordingly, the audible cues sound somewhat less harsh in quiet environments at the expense of some loss in intelligibility in more noisy environments. 
     The first alternative embodiment operates largely in a similar manner as the basic embodiment described above. Thus the sound level of the ambient noise of the environment is determined using a microphone  202  and sound level calculation component  208 . However, the first alternative embodiment includes a harmonic processor  312  to add harmonically related frequency content to the audible cue to enhance intelligibility at higher sound levels. In other words, when the sound level calculation determines that the medical device is operating in a louder ambient sound level, the gain of the amplifier is increased to raise the sound level of the audible cue. In addition, the harmonic processor  312  dynamically alters the sound files to include harmonics that enhance the intelligibility of the audible cues in noisy environments. Accordingly, the audible cues sound less harsh in quiet environments where masking is less of a problem, but harshness is added (e.g., via third and fifth harmonics) to enhance intelligibility in a noisy environment. 
     As can be seen, the first alternative embodiment  300  produces more sound level when needed and also introduces harmonically-related spectral content to the output sound to enhance intelligibility at higher sound levels. The first alternative embodiment  300  improves greatly on the basic embodiment  200  for audibility in ambient noise. 
       FIG. 4  is a functional block diagram illustrating components of a second alternative embodiment  400  that improves on the first alternative embodiment of  FIG. 3 . As above, components shown in  FIG. 4  operate in the same manner as similarly-labeled components shown in  FIGS. 2 and 3 . However, the sound library  401  of the second alternative embodiment includes sound files that are more processed to enhance noisy-environment intelligibility (similar to the sound files used in the basic embodiment) and sound files that are less processed (similar to the sound files used in the first alternative embodiment). Accordingly, each of the audible cues may have at least two (but possibly more) corresponding sound files; at least one which sounds better in quieter environments and at least another that sounds better in louder environments. Of course, there may be certain audible cues for which alternative sound files are not necessary. 
     In accordance with this embodiment, a sound level spectrum knowledge base  410  is included which stores information about the spectral characteristics of typical maskers (i.e, competing noises which may mask the audible cues) in particular noise environments. In other words, based on prior evaluations and analysis, this embodiment incorporates a priori knowledge regarding particular noise contributors in various different ambient environments. In this manner, a basic psycho-acoustic enhancement processor (PAEP)  412  receives sound level information from the sound level calculation component  208  with an estimate of an appropriate gain that should be applied to a sound file based on the current ambient environment (via gain estimator  414 ). 
     The PAEP  412  uses the measurement of ambient sound level in combination with the knowledge base  410  of environmental noise levels. Based on (at least) those two inputs, the PAEP  412  determines which one of the several pre-processed sounds within sound library  401  best fit the ambient situation. Gain to the amplifier  212  may also be adjusted for enhanced use of the chosen pre-processed sound. The pre-processed sounds within library  401  have their spectral content adjusted based on one of many possible psycho-acoustic formulae for determining critical band frequencies of the basilar membrane. The spectral content of each specific sound is pre-processed to correspond with the various ambient sound level situations in the knowledge base  410 . 
       FIG. 5  a functional block diagram illustrating components of a third alternative embodiment  500  that improves on the first and second alternative embodiments of  FIGS. 3 and 4 . As above, components shown in  FIG. 5  operate in the same manner as similarly-labeled components shown in FIGS.  2 ,  3  and  4 . However, the sound library  501  of the third alternative embodiment may include sound files that are less processed to enhance noisy-environment intelligibility (similar to the sound files used in the first alternative embodiment). The sound library  501  of the third alternative embodiment may, but need not, also include sound files that are more processed (similar to the sound files used in the basic embodiment) for noisy-environment intelligibility. 
     The third alternative embodiment  500  includes a microphone  202  and ancillary components to detect both sound level (i.e., sound level calculation component  208 ) and sound spectrum (i.e., sound spectrum analysis component  508 ) of the ambient environment. Measurements of those two parameters are used to create estimates of predicted auditory masking of the device sounds, via a spectrum enhancement estimation component  510 . A psycho-acoustic model of changes to the source sound spectrum emerges in real-time which may be used to make the source sounds more resistant to masking in the presence of potentially masking sounds of the ambient environment. In this embodiment, an advanced PAEP  512  predicts necessary changes to both sound level and spectral content dynamically to enhance the sound output of the medical device for a given environment. 
     In most embodiments, a hold function (not shown) should be used to prevent changes to the sensed ambient sound level and adjustments to the sound output during the period when the device is itself generating sound (e.g., while playing an audible cue). This avoids making inappropriate adjustments based on the device contribution to the ambient environment. 
     Sample spectrograms will now be presented to help illustrate the operation of the above-described embodiments. In particular, the sample spectrograms shown in  FIGS. 9-14  provide guidance regarding the processing of sound files for use in the embodiments illustrated in  FIGS. 2-5  and described above. As with  FIGS. 6-8 , the “X” axis denotes time; 0 to 10 seconds. The “Y” axis represents frequency; 0 to 4000 Hz. Sound levels are represented by brightness on the spectrogram; brighter is higher sound level, darker is lower sound level. 
       FIG. 9  is a sample spectrogram showing an audible cue processed to include harmonics of the audible cue. Altering the sound spectrum of the audible cue such that energy is redistributed to the harmonics creates redundancies in non-overlapping auditory critical bands. 
       FIG. 10  is a sample spectrogram showing the altered audible cue of  FIG. 9  in combination with the masker signal shown in  FIG. 8 . As illustrated, when the 400 Hz single-frequency masker signal of  FIG. 8  is presented with the altered audible cue of  FIG. 9 , the 400 Hz masker dominates the fundamental of the altered alert sound, but does not mask the higher harmonics. Thus, the altered alert audible cue is more robust to masking by a single frequency sound. 
       FIG. 11  is a sample spectrogram showing the altered audible cue of  FIG. 9  in combination with a masker signal having harmonics. As shown, if the altered audible cue may still be at risk of being hard to hear or even inaudible in the same environment as the masker signal with harmonic content. It will be appreciated that this depends on proximity of the masking sound harmonics to the altered audible cue harmonics and if they are both within a critical bandwidth of each other. 
       FIG. 12  is a sample spectrogram illustrating an audible cue altered in accordance with characteristics of the human auditory system. More specifically, the adjustments to the audible cue are based on the psycho-acoustic concept of a Critical Bandwidth (“CB”) that forms on the basilar membrane when stimulated. The basilar membrane is located within the cochlea in the inner ear. Generally stated, the critical bandwidth is the band of audio frequencies within which a second tone will interfere with the perception of a first tone by auditory masking. One such estimation of the critical bandwidth is presented below: 
     
       
         
           
             CB 
             ⁢ 
             
               = 
               
                 
                   2 
                   ⁢ 
                   5 
                 
                 + 
                 
                   7 
                   ⁢ 
                   
                     
                       5 
                       ⁡ 
                       
                         [ 
                         
                           1 
                           + 
                           
                             1.4 
                             ⁢ 
                             
                               
                                 ( 
                                 
                                   
                                     freq 
                                     / 
                                     1 
                                   
                                   ⁢ 
                                   0 
                                   ⁢ 
                                   0 
                                   ⁢ 
                                   0 
                                 
                                 ) 
                               
                               ⩓ 
                             
                             ⁢ 
                             2 
                           
                         
                         ] 
                       
                     
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                   0.69 
                   ⁢ 
                   
                       
                   
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     *Zwicker, Eberhard, Journal of Acoustical Society of America, November 1980 
     (This formula is but one example of many different equally-applicable formulae, as will be apparent to those skilled in the art.) 
       FIG. 13  is a sample spectrogram illustrating the CB altered audible cue of  FIG. 12  combined with the masking signal of  FIG. 8 . As is evident from  FIG. 13 , the CB altered audible cue is extremely robust to single frequency masking. 
       FIG. 14  is a sample spectrogram illustrating the CB altered audible cue of  FIG. 12  combined with the masking signal having harmonics. As is evident from  FIG. 14 , even when presented with a masking sound containing harmonic content, the CB altered audible cue remains audible as it is stimulating non-overlapping CBs of the basilar membrane and the spectral content is spread to avoid the harmonics of maskers. 
     In this description, numerous details have been set forth in order to provide a thorough understanding. In other instances, well-known features have not been described in detail in order to not obscure unnecessarily the description. 
     A person skilled in the art will be able to implement these additional embodiments in view of this description, which is to be taken as a whole. The specific embodiments disclosed and illustrated herein are not to be considered in a limiting sense. Indeed, it should be readily apparent to those skilled in the art that what is described herein may be modified in numerous ways. Such ways can include equivalents to what is described herein. 
     For example, in another embodiment for use in cars, trains, buses, planes, or other noisy environments in which audio announcements are made, a system may include a microphone configured to capture ambient noise; a sound library including a plurality of sound files, each sound file corresponding to an audible cue; an amplifier coupled to a speaker, the amplifier having a selectable gain and being configured to output each of the plurality of sound files over the speaker; a sound level detection component coupled to the microphone and configured to detect a sound level of the ambient noise; a sound spectrum detection component coupled to the microphone and configured to detect spectrum characteristics of the ambient noise; a sound spectrum analysis component coupled to the sound spectrum detection component and being configured to provide an estimate of an amount of gain to apply to tile amplifier based on an analysis of the spectral characteristics of the ambient noise; and a sound altering component configured to alter the selectable gain of tile amplifier based on the sound level of the ambient noise in conjunction with the estimate, or to alter harmonic content of the sound files based on the spectral characteristics of the ambient noise, or both. 
     In addition, various embodiments may be practiced in combination with other systems or embodiments. The following claims define certain combinations and subcombinations of elements, features, steps, and/or functions, which are regarded as novel and non-obvious. Additional claims for other combinations and subcombinations may be presented in this or a related document