Non-invasive transducer health detection

Abstract

Embodiments for non-invasive transducer health detection in an audio system are disclosed. In embodiments, a method performed by an audio system includes outputting one or more encoded inaudible acoustic signals into an acoustic transmission medium using a first transducer. One or more encoded inaudible acoustic signals are received from the acoustic transmission medium using a second transducer of the audio system. A failure or degradation of the first or second transducer is identified using the received one or more encoded inaudible acoustic signals.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 041685, filed June 19, 2020, and European Patent Application No. 20181112.2, filed June 19, 2020, both of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure generally relates to detecting faulty transducers (e.g., speakers, microphones) in audio systems. Background Technology

[0004] Audio systems typically include multiple sound transducers, such as speakers and microphones. In many audio applications, users of audio systems often struggle to determine if a transducer is faulty. In television applications, audible test tones are played to test speakers. However, these test tones can be distracting for users, and in the case of managed equipment, it's not the user's responsibility. In cinema applications, detecting damaged speakers or microphones is expensive because it requires removing the audio system from service for inspection and repair. In video conferencing applications using beamforming or position mapping, if one microphone is more degraded than another, the beamformer will point in the wrong direction, which is difficult for users to detect. While built-in open-circuit and short-circuit detection techniques are frequently used in traditional audio systems, these techniques cannot detect different types of acoustic degradation. Summary of the Invention

[0005] This invention generally relates to non-invasive transducer health detection in audio systems. A first aspect of the invention relates to a method performed by an audio system, comprising: encoding a test signal onto an inaudible acoustic signal; outputting the encoded inaudible acoustic signal to an acoustic transmission medium using a first transducer of the audio system; receiving the encoded inaudible acoustic signal from the acoustic transmission medium using a second transducer of the audio system; recovering a recovered test signal from the received encoded inaudible acoustic signal; and using the recovered test signal to identify a fault or degradation in either the first or second transducer.

[0006] In this embodiment, a pseudo-random binary sequence is used to encode the inaudible signal. The pseudo-random binary sequence can be a maximum-length sequence.

[0007] In an embodiment, the recovered test signal is correlated with (e.g., compared with) a (known) test signal to identify a fault or degradation.

[0008] In this embodiment, the impulse response of the audio system is determined based on the recovered test signal and the relationship between the test signals. Furthermore, changes in the signal-to-noise ratio (SNR) of the impulse response can be used to identify a fault or degradation in at least one of the first or second transducers.

[0009] In an embodiment, based on identifying a fault or degradation in at least one of the first or second transducers, the audio system initiates at least one of the following: disabling at least one transducer, adjusting the input / output signal processing of at least one transducer, or initiating one or more additional diagnostic tests on at least one transducer.

[0010] In one embodiment, the audio system includes a first plurality of transducers and a second plurality of transducers. The first plurality of transducers output a plurality of encoded inaudible acoustic signals to an acoustic transmission medium, each inaudible acoustic signal having a different encoding. The audio system receives the plurality of encoded inaudible acoustic signals from the acoustic transmission medium using the second plurality of transducers. The audio system uses the received plurality of encoded inaudible acoustic signals to identify a fault or degradation of at least one of the first or second plurality of transducers. The plurality of encoded inaudible acoustic signals are output to the acoustic transmission medium in parallel or one at a time.

[0011] In an embodiment, using the received plurality of encoded inaudible acoustic signals to identify a fault or degradation of at least one of the first or second plurality of transducers includes: measuring the impulse response of the audio system of the first and second transducer pairs, and using the impulse response to identify the fault or degradation.

[0012] In an embodiment, using a plurality of received encoded inaudible acoustic signals to identify a fault or degradation of at least one of the first or second plurality of transducers includes: determining the signal-to-noise ratio of the impulse response; comparing the signal-to-noise ratios to determine an outlier signal-to-noise ratio; and using the outlier signal-to-noise ratio to identify a fault or degradation of at least one of the first or second transducers.

[0013] In the embodiments, signal-to-noise ratio (SNR) is used to calculate statistics or metrics, and each SNR is compared to the mean, and outlier SNRs are determined based on the comparison with the mean.

[0014] Other aspects of the invention disclosed herein relate to a system, apparatus, and computer-readable medium. Details of the disclosed implementations are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will become apparent from the specification, drawings, and claims.

[0015] The specific embodiments disclosed herein provide one or more of the following advantages. Different types of acoustic degradation of the transducer are automatically detected by the audio system without playing intrusive audible test tones or taking the audio system out of service for inspection and repair. Attached Figure Description

[0016] Various embodiments are illustrated in the accompanying drawings, block diagrams, flowcharts, and other figures. Each block in a flowchart or block may represent a portion of a module, program, or code containing one or more executable instructions for performing a specified logical function. While these blocks are shown in a specific order for performing method steps, they are not necessarily executed in a strictly regulated order. For example, they may be executed in reverse order or simultaneously, depending on the nature of the respective operations. It should also be noted that each block and combination thereof in the block diagrams and / or flowcharts may be implemented by a software-based or hardware-based dedicated system for performing the specified function / operation, or by a combination of dedicated hardware and computer instructions.

[0017] Figure 1 This is a block diagram of a non-invasive transducer health monitoring system according to an embodiment.

[0018] Figure 2 According to the embodiments, by Figure 1 The diagram shows the signal processing performed by the signal recognizer.

[0019] Figure 3 According to the embodiments, by Figure 1 and Figure 2 The diagram shows the signal processing performed by the transducer health rating unit.

[0020] Figure 4 This is a flowchart of a non-invasive transducer health monitoring process according to an embodiment.

[0021] Figure 5 This is a block diagram of an audio system architecture including non-invasive transducer health detection according to an embodiment.

[0022] The same reference numerals used in various figures indicate the same elements. Detailed Implementation

[0023] Nomenclature

[0024] As used herein, the term “comprising” and its variations shall be understood as open-ended terms meaning “including but not limited to”. Unless the context clearly indicates otherwise, the term “or” shall be understood as “and / or”. The term “based on” shall be understood as “at least partially based on”. The terms “one example embodiment” and “example embodiment” shall be understood as “at least one example embodiment”. The term “another embodiment” shall be understood as “at least one other embodiment”. Furthermore, in the following description and claims, unless otherwise defined, all technical and scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0025] System Overview

[0026] Figure 1 This is a block diagram of a non-invasive transducer health monitoring system 100 according to an embodiment. System 100 includes an optional anti-aliasing filter (AAF) 101, transducers 102 and 103, a signal identifier 104, a transducer health rating unit 105, and a transducer manager 106. In this example embodiment, transducer 102 is a speaker, and transducer 103 is a microphone. System 100 may include any number and type of transducers. System 100 can be implemented in audio systems to help users, IT departments, and / or manufacturers diagnose problems in the audio signal chain. Some example audio systems include, but are not limited to: teleconferencing endpoints, videoconferencing endpoints, cinema audio systems, smart speakers, televisions, home theater systems, live concert microphone / speaker / monitor setups, and connected Internet of Things (IoT) devices.

[0027] In this embodiment, the test signal is encoded onto the inaudible acoustic signal by a modulator circuit (not shown) that modulates the inaudible acoustic signal with a test signal (e.g., a pseudo-random binary sequence), and the modulated inaudible signal is output to the acoustic transmission medium via transducer 102. In this embodiment, the inaudible signal is an ultrasonic signal. In this embodiment, the inaudible signal is a signal within the range of human hearing, but is inaudible due to its sound pressure level (SPL) or due to psychoacoustic masking with other acoustic signals. In this embodiment, the inaudible signal is a subsonic signal. The "audibility" of a particular inaudible signal can be determined offline using an assumed background noise level, or online by measuring the background noise level in the case of a multi-microphone / speaker system.

[0028] In this embodiment, any type of analog or digital modulation is used to encode the inaudible signal, including but not limited to: amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), quadrature amplitude modulation (QAM), and binary phase shift keying (BPSK). In this embodiment, the modulated signal drives a loudspeaker that outputs the encoded inaudible acoustic signal to the acoustic transmission medium. In this embodiment, a mixer combines the inaudible signal with another signal (e.g., an audio signal) to produce an acoustic signal output through the loudspeaker to the acoustic transmission medium.

[0029] In embodiments where the inaudible signal is an ultrasonic signal, the inaudible transducer is a piezoelectric or capacitive transducer, and the ultrasonic signal has a frequency higher than the human audible frequency range (e.g., >20 kHz). In embodiments, the test signal for encoding / modulating the inaudible signal is a maximum length sequence (MLS) generated using a maximum linear feedback shift register. The MLS helps prevent false positives from other inaudible signals (e.g., false positives from whistling capacitors). Each inaudible signal can be encoded / modulated using a different MLS and / or encoded / modulated with different carrier signals having different carrier frequencies.

[0030] In one embodiment, the inaudible signal is processed by an AAF 101 (e.g., a low-pass filter) before being played through a transducer 102 (e.g., a loudspeaker) to the acoustic transmission medium.

[0031] Transducer 103 (e.g., a microphone) receives or captures inaudible acoustic signals (hereinafter also referred to as "received signals") from the environment and outputs the received signals to signal recognizer 104. Signal recognizer 104 processes the received signals to recover a recovered test signal (a recovered version of the test signal). A fault or degradation of either transducer 102 or 103 can now be determined based on the relationship between the recovered test signal and the original test signal. For example, if an MLS is used as the test signal, the total impulse response of the transducer (the impulse response of transducers 102 and 103 plus the impulse response of the channel ("room")) is determined using the cyclic cross-correlation on the recovered MLS (the recovered test signal) and the original MLS (the test signal). The signal-to-noise ratio (SNR) of the impulse response is calculated and input to transducer health rating unit 105. In some cases, inaudible acoustic signals may not be recognized by signal recognizer 104, indicating a transducer fault. In this case, a corrective action (e.g., disabling the transducer) is initiated by transducer health manager 106 without further analysis.

[0032] In one embodiment, the transducer health rating unit 105 determines the health of transducers 102 and 103 by comparing the signal-to-noise ratio (SNR) of the impulse response calculated by the signal identifier 104 with one or more thresholds. For example, if the SNR is below a specified threshold, transducer 102 or transducer 103 is assumed to be degraded. In an embodiment, if the impulse response of a channel (also referred to as the “room impulse response”) is known, it can be used to determine the threshold to avoid false positives. For example, even if the transducer is not degraded, the room may attenuate the received signal. In an embodiment, the impulse response is gated to remove room reflections that may affect the impulse response and frequency response of the speaker / microphone pair being tested.

[0033] Transducer health rating unit 105 outputs health ratings for transducers 102 and 103 to transducer health manager 106. Transducer health manager 106 initiates one or more actions in response to the health rating, such as disabling one or both transducers 102 and 103, altering the signal path or adjusting audio signal processing (e.g., adjusting multi-channel audio rendering), and / or initiating further diagnostic tests for transducers 102 and 103 (e.g., sine sweep test, manual test steps). In an embodiment, the characteristics of transducers 102 and 103 are measured over time to determine the slow degradation of transducers 102 and 103, allowing for the scheduling of audio system maintenance.

[0034] In embodiments, various characteristics of the impulse response in the time domain (e.g., peak amplitude rise time, settling time) or frequency response can be used to identify specific types of acoustic degradation. For example, the measured impulse response characteristics can be compared with a lookup table of reference impulse response characteristics associated with a specific transducer problem. In embodiments, a Fast Fourier Transform (FFT) or other transforms (e.g., Discrete Cosine Transform (DCT), Short-Time Fourier Transform (STFT)) can be applied to the time-domain impulse response to obtain the frequency response. From the frequency response, a spectral “signature” (e.g., energy distribution over the frequency range of interest) can be identified and compared with known spectral features associated with a specific type of acoustic degradation. Table I summarizes the types of acoustic degradation that system 100 may or may not detect.

[0035] Table I - Types of Acoustic Degradation

[0036]

[0037] The aforementioned system 100 non-invasively detects different types of acoustic degradation caused by transducer health without playing audible test tones or shutting down the audio system for repair. However, system 100 cannot determine which transducer is degraded. In systems with multiple transducers, such as speaker arrays and microphone arrays in video conferencing systems or cinema applications, specific transducers in the signal path can be identified, as referenced in [reference]. Figure 2 and Figure 3 A more comprehensive description.

[0038] Figure 2 Provided according to the embodiments Figure 1 A block diagram showing further details of the signal processing performed by the system 100 shown. In the illustrated example embodiment, as referenced... Figure 1 As described, the loudspeaker array 201 includes a plurality of loudspeakers that transmit inaudible acoustic signals 1...n into a channel (acoustic transmission medium). In an embodiment, frequency division multiplexing (FDM) is used to transmit the inaudible acoustic signals 1...n.

[0039] Microphone array 202 includes multiple microphones. Each microphone in microphone array 202 captures inaudible acoustic signals 1...n emitted by speakers in speaker array 201. In an embodiment, an analog front end (AFE) is included in a signal path (not shown) that includes a microphone interface (e.g., an XLR port), an amplifier for amplifying the microphone output signal, and an analog-to-digital converter (ADC) for converting the amplified microphone output signal into a digital value for input to DSP 203.

[0040] DSP 203 includes a demultiplexer 204 for demultiplexing the microphone output signal to recover a recovered test signal (a recovered version of the test signal). Depending on the format of the received signal, demultiplexer 204 may include a time-demultiplexer, a demodulator, and / or a decorrelation unit.

[0041] Notice, Figure 2 An example use case is shown in which multiple encoded inaudible acoustic signals are output in parallel from speaker array 201. In other embodiments, inaudible acoustic signals are output through one speaker at a time. Similarly, each microphone in microphone array 202 can be activated one at a time to capture the output of the activated speaker. In this way, all possible signal paths through all possible speaker / microphone pairs can be analyzed serially. In embodiments where inaudible acoustic signals are transmitted in parallel, DSP 203 decorrelates or demultiplexes the received signals to recover the test signal.

[0042] As will be referred to later Figure 3As described, each speaker / microphone pair plus channel has a unique impulse response, which changes if one or both speakers or microphones degrade. MLS is used to measure the impulse response of the speaker / microphone pair. To facilitate comparison between speaker / microphone pairs, the SNR of each impulse response is calculated and used to determine the outlier SNR including one or more degraded transducers. The overall impulse response of each speaker / microphone pair will also include the channel or "room impulse response". However, since the speaker / microphone pair will experience the same "room impulse response" and each is compared with the SNR, the "room impulse response" will not affect the system's health detection capability.

[0043] The recovered test signal is input to the transducer health rating unit 105, which uses the recovered test signal and the original test signal to calculate the impulse response of the speaker and microphone pair. For the MLS test signal, the impulse response of the speaker / microphone pair can be measured using cyclic cross-correlation or other known techniques, utilizing the recovered MLS (recovered test signal) and the original MLS (test signal) used to encode the inaudible signal.

[0044] The transducer health rating unit 105 also calculates the signal-to-noise ratio (SNR) for each impulse response. The SNR is compared to a threshold to detect outlier SNRs. In an embodiment, an average SNR is calculated, and each SNR is compared to this average to detect outlier SNRs based on a standard deviation or quartile range metric. For example, a signal-to-noise ratio with a standard deviation greater than 3σ is considered an outlier SNR, and it is assumed that speaker / microphone pair degradation is associated with such an outlier SNR.

[0045] As described above, in response to a health rating from the transducer health rating unit 105, the transducer health manager 106 initiates one or more actions, such as initiating a transducer disablement, changing the signal path or adjusting the processing of the audio signal (e.g., adjusting the rendering of multi-channel audio), and / or initiating further diagnostic tests for the transducer (e.g., sine sweep test, manual test steps).

[0046] Figure 3 According to the embodiments, by Figure 1The diagram shows a block diagram of the signal processing performed by the transducer health rating unit 105. In the example shown, system 300 includes an impulse response generator 301, an SNR calculator 302, and an SNR comparison module 303. Demultiplexed test signals and the original test signals are input to the impulse generator 301, which generates impulse responses H1...Hn. If the baseband signal is an MLS, the impulse response of the speaker / microphone pair can be measured using cyclic cross-correlation or other known techniques. The impulse responses H1...Hn are input to the SNR calculator 302, which calculates the SNR of the impulse responses. In an embodiment, the SNR can be calculated as the root mean square (RMS) of the impulse response H(k) divided by the base-10 logarithm of the RMS of the sampled noise n(k), multiplied by 10, where k is an exponent with an integer value from 1 to N. In an embodiment, when the speaker is not emitting any sound, noise n(k) is captured from the surrounding environment using one or more of a plurality of microphones. SNR comparison module 303 compares SNRs by calculating the mean and standard deviation of SNRs, and identifies SNRs that exceed a specified standard deviation (e.g., 3σ) as outlier SNRs.

[0047] In the example shown, microphone / speaker pair 3 has a standard deviation exceeding the specified standard deviation and is identified as an outlier SNR. SNR comparison module 303 compares the values ​​of the transducer health manager 106 (…). Figure 2 The transducer health manager 106 outputs a transducer health report indicating that microphone / speaker pair 3 has failed, allowing the transducer health manager 106 to perform corrective actions. Some examples of corrective actions include, but are not limited to: disabling the speaker and / or microphone; replacing the faulty speaker / microphone with a different speaker or microphone; adjusting the signal processing of the audio signal; and / or performing additional diagnostic tests, such as generating a linear or exponentially sweeping sine wave and comparing the resulting frequency response with a known frequency response indicating the type of acoustic degradation.

[0048] In this embodiment, pairwise comparisons of SNR are used to identify whether a speaker, microphone, or both are degraded. For example, suppose an audio system has two speakers and two microphones. Table II shows how to identify degraded transducers using pairwise comparisons.

[0049] Table II - Examples of Degraded Transducer Identification

[0050] speaker# microphone# SNR Speaker_1 Microphone_1 No attenuation Speaker_1 Microphone_2 attenuation Speaker_2 Microphone_1 No attenuation Speaker_2 Microphone_2 attenuation

[0051] As shown in Table II above, microphone_2 is the common transducer (in bold) when attenuation is observed. In this example, microphone_2 is disabled, and / or signal processing on the audio signal is adjusted and / or additional diagnostic tests on microphone_2 are initiated, such as playing a linear or exponentially swept sine wave and analyzing the resulting frequency response.

[0052] In one embodiment, the transducer health manager 106 generates control signals and / or data to disable a degraded transducer. For example, one or more control signals are sent to electronic or mechanical switches or relays that connect / disconnect a speaker or microphone from an audio amplifier. In another embodiment, one or more control signals are sent to one or more digital signal processors to adjust the signal processing of the audio signal, such as adjusting the orchestration audio protocol; adjusting audio object rendering or rerouting audio to different speakers in a multichannel audio system; adjusting microphone beamforming (e.g., disabling one microphone in a microphone array to produce mono audio using the remaining "good" microphones); providing graceful degradation in a multichannel audio system to allow continued use of the multichannel audio system; or providing triggers for audible stimuli to deliver better diagnostic results (e.g., linear or exponentially swept sine wave techniques).

[0053] Example process

[0054] Figure 4 This is a flowchart of a non-invasive transducer health monitoring process 400 according to an embodiment. Process 400 can be used... Figure 5 The audio system architecture shown is used to implement this.

[0055] Process 400 begins with receiving an encoded inaudible signal (401) for transducer health detection. In embodiments employing multiple loudspeakers and / or microphones, a different test signal may be used for each loudspeaker. Each inaudible signal is generated (e.g., encoded / modulated) using different test signals (e.g., different MLSs) using any known encoding or modulation scheme (e.g., ASK, FSK, PSK, QAM, BPSK). In embodiments, frequency division multiplexing (FDM) is used to transmit the encoded inaudible signal into the acoustic transmission medium. The inaudible signal may be an ultrasonic signal, a subsonic signal, or a quiet signal with a low SPL level.

[0056] Process 400 continues by demultiplexing the encoded inaudible signals to provide a recovered version of the test signal (402). For example, one or more microphones capture the inaudible signals, and an optional AFE applies signal conditioning (e.g., filtering, amplification, analog-to-digital conversion) to the inaudible signals to recover the test signal (e.g., recovering the MLS from each inaudible signal). In embodiments with multiple speakers having parallel output encoded inaudible signals, the encoded inaudible signals are decorrelated by a DSP so that they can be processed separately.

[0057] Process 400 continues by determining the impulse response of the transducer pair using the recovered test signal and the original test signal (403). After demultiplexing / decorrelated, each test signal is associated with the transducer pair (speaker and microphone). If the test signal is an MLS, cyclic cross-correlation or other suitable techniques are used to determine the impulse response of the combination of speaker, channel, and microphone.

[0058] Process 400 continues by determining the SNR (404) of the impulse response. For example, when no audible signal is present, the microphone can capture noise samples from the local surrounding environment. In an embodiment, if the noise is assumed to be stable and white, a constant value can be used as the noise. In an embodiment, the SNR is the base-10 logarithm of the RMS of the impulse response divided by the RMS of the noise samples, multiplied by 10.

[0059] Process 400 continues by analyzing the SNR to determine the outlier SNR (405). In an embodiment, the mean and standard deviation of the SNR are calculated, and the outlier SNR is determined based on the standard deviation. In an embodiment, an SNR greater than 1.5 interquartile ranges (IQRs) below the first quartile or above the third quartile is an outlier value. Other methods for determining outlier SNRs, such as machine learning (e.g., k-means clustering, neural networks), can also be used.

[0060] Process 400 continues by identifying degraded (multiple) transducers (406) based on the determined outlier SNR.

[0061] Example audio system architecture

[0062] Figure 5 This is a block diagram of an audio system architecture 500 including non-invasive transducer health detection according to an embodiment. In this example, the audio system architecture 500 is used in a video conferencing system and includes: a central processing unit (CPU) 501 for executing instructions to perform various tasks; a memory 502 for storing instructions and data (e.g., flash memory, RAM, ROM); a network interface 503 for connecting to a network; and a non-invasive transducer health detector 504 for automatically monitoring the health status of transducers (speakers and microphones), as referenced. Figure 1-4 The described interface includes: a video interface 505, coupled to a video display 506, for displaying the participant's video; a speaker interface, coupled to a speaker array 508, for outputting the participant's voice; a microphone interface 509, coupled to a microphone array 510, for capturing the participant's voice; and a camera interface 511, coupled to a camera 512, for capturing the participant's video. Each of these components is coupled to one or more buses 513 and communicates with each other thereon. Each of interfaces 505, 507, 509, and 511 includes circuitry for signal conditioning, such as filters, amplifiers, power supplies, data buffers, clocks, and any other circuitry required to interface with its respective input or output device.

[0063] Other audio systems that can perform non-invasive transducer health detection include, but are not limited to, audio systems used in cinemas, smart speakers, and any other audio system that includes at least one transducer.

[0064] Various aspects of the invention can be understood from the following enumerated example embodiments (EEE):

[0065] EEE 1. A method performed by an audio system, comprising:

[0066] The first transducer of the audio system outputs an encoded, inaudible signal into the acoustic transmission medium;

[0067] The second transducer of the audio system receives an encoded inaudible signal from the sound transmission medium; and

[0068] The received coded inaudible signal is used to identify a fault or degradation in at least one of the first or second transducers.

[0069] EEE 2. The method according to EEE 1, wherein the received inaudible signal is an ultrasonic signal.

[0070] EEE 3. The method according to any one of EEE 1-2 above, wherein the received inaudible signal is encoded using a pseudo-random binary sequence.

[0071] EEE 4. The method described in EEE 3, wherein the pseudo-random binary sequence is a maximum length sequence.

[0072] EEE 5. The method according to any one of EEE 1-4 above, wherein the first transducer is a loudspeaker and the second transducer is a microphone.

[0073] EEE 6. The method as described in any one of EEE 1-5 above, wherein using the received coded inaudible signal to identify a fault or degradation in at least one of the first or second transducers comprises: using the coded inaudible signal to measure the impulse response of the audio system, and using the impulse response to identify a fault or degradation in at least one of the first or second transducers.

[0074] EEE 7. The method according to EEE 6, wherein using the received encoded inaudible signal to identify a fault or degradation in at least one of the first or second transducers comprises: determining the signal-to-noise ratio (SNR) of the impulse response and identifying changes in the SNR.

[0075] EEE 8. The method according to any one of EEE 1-7 above, further comprising:

[0076] Based on the identification of a fault or degradation in at least one of the first or second transducers, the audio system initiates at least one of the following: disabling at least one of the first or second transducers, adjusting the input or output signal processing of at least one of the first or second transducers, or initiating one or more additional diagnostic tests on at least one of the first or second transducers.

[0077] EEE 9. The method according to any one of EEE 1-8 above, wherein the audio system includes a first plurality of transducers and a second plurality of transducers, the method further comprising:

[0078] The first plurality of transducers of the audio system output multiple encoded inaudible signals to the acoustic transmission medium, each encoded inaudible signal having a different encoding;

[0079] The audio system uses a second plurality of transducers to receive the plurality of encoded inaudible signals from the sound transmission medium; and

[0080] The received plurality of encoded inaudible signals are used to identify a fault or degradation of at least one of the first or second plurality of transducers.

[0081] EEE 10. The method according to EEE 9, wherein using the received plurality of encoded inaudible signals to identify a fault or degradation of at least one of the first or second plurality of transducers comprises: measuring the impulse response of the audio system for the first and second transducer pairs, and using the impulse response to identify the fault or degradation.

[0082] EEE 11. The method according to EEE 10, wherein using a plurality of received encoded inaudible signals to identify a fault or degradation of at least one of the first or second plurality of transducers comprises: determining the signal-to-noise ratio of the impulse response; comparing the signal-to-noise ratios to determine an outlier signal-to-noise ratio; and using the outlier signal-to-noise ratio to identify a fault or degradation of at least one of the first or second transducers.

[0083] EEE 12. The method according to EEE 11 further includes:

[0084] Use signal-to-noise ratio to calculate statistics or measures;

[0085] Compare each signal-to-noise ratio to the average; and

[0086] The outlier signal-to-noise ratio is determined by comparing it with the average value.

[0087] EEE 13. An audio system comprising:

[0088] First transducer;

[0089] Second transducer;

[0090] The circuit is configured as follows:

[0091] The first transducer is used to output the encoded inaudible signal into the acoustic transmission medium;

[0092] Using a second transducer to receive an encoded inaudible signal from the sound transmission medium; and

[0093] The processor is configured to execute any of the aforementioned EEE 1-12.

[0094] EEE 14. A non-transient computer-readable storage medium having instructions stored thereon, the instructions causing one or more processors, when executed by one or more processors of an audio system, to perform any of the methods described in EEE 1-12 above.

[0095] EEE 15. An apparatus comprising:

[0096] A first transducer is configured to receive an encoded inaudible signal from an acoustic transmission medium, the encoded inaudible signal being output by a second transducer; and

[0097] The processor is configured as follows:

[0098] The impulse response of an audio system comprising a first transducer and a second transducer is measured using a received encoded inaudible signal.

[0099] Identifying faults or degradation in at least one of the first or second transducers based on the impulse response of the audio system; and

[0100] Initiate at least one of the following: disable at least one of the first or second transducers, adjust the input or output signal processing of at least one of the first or second transducers, or initiate one or more additional diagnostic tests on at least one of the first or second transducers.

[0101] While this document contains numerous specific implementation details, these details should not be construed as limiting the scope of possible claims, but rather as descriptions of features that may be specific to particular embodiments. Certain features described in this specification within the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Furthermore, although features may be described above as functioning in certain combinations, and even initially claimed to be so, in some cases, one or more features from the claimed combination may be removed from the combination, and the claimed combination may be directed to sub-combinations or variations thereof. The logical flows described in the accompanying drawings do not require the specific order or sequence shown to achieve the desired results. Furthermore, additional steps may be provided or removed from the described flow, and additional components may be added to or removed from the described system. Therefore, other implementations are within the scope of the appended claims.

Claims

1. A method performed by an audio system, comprising: The test signal is encoded onto an inaudible acoustic signal; The first transducer of the audio system outputs an encoded, inaudible acoustic signal into the acoustic transmission medium. The encoded inaudible acoustic signal is received from the acoustic transmission medium using the second transducer of the audio system; The recovered test signal is extracted from the received encoded inaudible acoustic signal; Using the recovered test signal to identify a fault or degradation in at least one of the first or second transducers, wherein using the recovered test signal to identify a fault or degradation further includes: The impulse response of the audio system is determined based on the recovered test signal and the test signal. Determine the background noise of the acoustic transmission medium; Based on the impulse response and the background noise, the signal-to-noise ratio (SNR) is determined; and Based on the SNR, a fault or degradation of at least one of the first or second transducers is identified.

2. The method as described in claim 1, wherein, The received inaudible signal is an ultrasonic signal.

3. The method according to any one of claims 1-2, wherein, The received inaudible signal is encoded using a pseudo-random binary sequence.

4. The method of claim 3, wherein, The pseudo-random binary sequence is a maximum-length sequence.

5. The method according to any one of claims 1-2, wherein, The first transducer is a loudspeaker, and the second transducer is a microphone.

6. The method of claim 1, wherein, Using the recovered test signal to identify faults or degradation also includes determining changes in the SNR.

7. The method according to any one of claims 1-2, further comprising: In response to identifying a fault or degradation in at least one of the first or second transducers, the audio system performs at least one of the following: Disable at least one of the first or second transducers. Adjust the input or output signal processing of at least one of the first or second transducers, or Perform one or more additional diagnostic tests on at least one of the first or second transducers.

8. The method according to any one of claims 1-2, wherein, The audio system includes a first plurality of transducers and a second plurality of transducers, and the method further includes: The first plurality of transducers of the audio system are used to output a plurality of encoded inaudible signals to the acoustic transmission medium, each encoded inaudible signal having a different encoding. Using the second plurality of transducers of the audio system to receive the plurality of encoded inaudible signals from the acoustic transmission medium; and Using the received plurality of coded inaudible signals to identify a fault or degradation of at least one of the first or second plurality of transducers, wherein using the received plurality of coded inaudible signals to identify a fault or degradation of at least one of the first or second plurality of transducers further comprises: Measure the impulse response of the audio system with respect to the first and second transducer pairs; Determine the signal-to-noise ratio of the impulse response; The signal-to-noise ratios are compared to determine the outlier signal-to-noise ratio; and The outlier signal-to-noise ratio is used to identify faults or degradation in at least one of the first or second transducers.

9. The method of claim 8, further comprising: Use the signal-to-noise ratio to calculate statistics or measures; Each signal-to-noise ratio is compared to the average value; as well as The outlier signal-to-noise ratio is determined based on a comparison with the average value.

10. An audio system, comprising: First transducer; Second transducer; The circuit is configured as follows: The test signal is encoded onto an inaudible acoustic signal; The first transducer is used to output an encoded inaudible signal into the acoustic transmission medium; The encoded inaudible signal is received from the acoustic transmission medium using the second transducer; as well as The processor is configured as follows: The recovered test signal is extracted from the received encoded inaudible acoustic signal; Using the recovered test signal to identify a fault or degradation in at least one of the first or second transducers, wherein using the recovered test signal to identify a fault or degradation in at least one of the first or second transducers includes: The impulse response of the audio system is determined based on the recovered test signal and the test signal. Determine the background noise of the acoustic transmission medium; Based on the impulse response and the background noise, the signal-to-noise ratio (SNR) is determined; and Based on the SNR, a fault or degradation of at least one of the first or second transducers is identified.

11. The audio system of claim 10, further comprising circuitry configured to activate at least one of the following in response to recognizing a fault or degradation in at least one of the first or second transducers: Disable at least one of the first or second transducers. Adjust the input or output signal processing of at least one of the first or second transducers, or Perform one or more additional diagnostic tests on at least one of the first or second transducers.

12. A non-transient computer-readable storage medium having instructions stored thereon, the instructions causing the one or more processors of an audio system to perform the method of any one of claims 1-9 when executed by the processors.

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