Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
  • H04R1/1083—Reduction of ambient noise
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/03—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters
  • G10L25/18—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters the extracted parameters being spectral information of each sub-band
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/48—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 specially adapted for particular use
  • G10L25/51—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 specially adapted for particular use for comparison or discrimination
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers, loudspeakers or microphones
  • H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S7/00—Indicating arrangements; Control arrangements, e.g. balance control
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
  • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
  • G10L21/0208—Noise filtering
  • G10L21/0216—Noise filtering characterised by the method used for estimating noise
  • G10L2021/02161—Number of inputs available containing the signal or the noise to be suppressed
  • G10L2021/02166—Microphone arrays; Beamforming
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/78—Detection of presence or absence of voice signals
  • G10L2025/783—Detection of presence or absence of voice signals based on threshold decision
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/78—Detection of presence or absence of voice signals
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/78—Detection of presence or absence of voice signals
  • G10L25/81—Detection of presence or absence of voice signals for discriminating voice from music
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
  • G10L25/78—Detection of presence or absence of voice signals
  • G10L25/84—Detection of presence or absence of voice signals for discriminating voice from noise
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2410/00—Microphones
  • H04R2410/05—Noise reduction with a separate noise microphone
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers, loudspeakers or microphones
  • H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones

Definitions

• the field of representative embodiments of this disclosure relates to methods, apparatuses, or implementations concerning or relating to playback management in an audio device.
• Applications include detection of certain ambient events, but are not limited to, those concerning the detection of near-field sound, proximity sound and tonal alarm detection using spatial processing based on signals received from multiple microphones.
• U.S. Pat. No. 8,804,974 teaches ambient event detection in a personal audio device which can then be used to implement an event-based modification of the playback content.
• the above-mentioned references also teach the use of microphones to detect various acoustic events.
• U.S. App. Ser. No. 14/324,286, filed on July 7, 2014 teaches using a speech detector as an event detector to adjust the playback signal during a conversation.
• one or more disadvantages and problems associated with existing approaches to event detection for playback management in a personal audio device may be reduced or eliminated.
• a method for processing audio information in an audio device may include reproducing audio information by generating an audio output signal for communication to at least one transducer of the audio device, receiving at least one input signal indicative of ambient sound external to the audio device, detecting from the at least one input signal a near-field sound in the ambient sound, and modifying a characteristic of the audio information reproduced to the at least one transducer in response to detection of the near-field sound.
• an integrated circuit for implementing at least a portion of an audio device may include an audio output configured to reproduce audio information by generating an audio output signal for communication to at least one transducer of the audio device, a microphone input configured to receive an input signal indicative of ambient sound external to the audio device, and a processor configured to detect from the input signal a near-field sound in the ambient sound and modify a characteristic of the audio information in response to detection of the near-field sound.
• a method for processing audio information in an audio device may include reproducing audio information by generating an audio output signal for communication to at least one transducer of the audio device, receiving at least one input signal indicative of ambient sound external to the audio device, detecting from the at least one input signal an audio event, and modifying a characteristic of the audio information reproduced to the at least one transducer in response to detection of the audio event being persistent for at least a predetermined time.
• an integrated circuit for implementing at least a portion of an audio device may include an audio output configured to reproduce audio information by generating an audio output signal for communication to at least one transducer of the audio device, a microphone input configured to receive an input signal indicative of ambient sound external to the audio device, and a processor configured to detect from the input signal an audio event and modify a characteristic of the audio information reproduced to the at least one transducer in response to detection of the audio event being persistent for at least a predetermined time.
• Figure 1 illustrates an example of a use case scenario wherein such detectors may be used in conjunction with a playback management system to enhance a user experience, in accordance with embodiments of the present disclosure
• Figure 2 illustrates an example playback management system that modifies a playback signal based on a decision from an event detector, in accordance with embodiments of the present disclosure
• FIG. 3 illustrates an example event detector, in accordance with embodiments of the present disclosure
• Figure 4 illustrates functional blocks of a system for deriving near-field spatial statistics that may be used to detect audio events, in accordance with embodiments of the present disclosure
• Figure 5 illustrates example fusion logic for detecting near-field sound, in accordance with embodiments of the present disclosure
• Figure 6 illustrates example fusion logic for detecting proximity sound, in accordance with embodiments of the present disclosure
• Figure 7 illustrates an embodiment of a proximity speech detector , in accordance with embodiments of the present disclosure
• Figure 8 illustrates example fusion logic for detecting a tonal alarm event, in accordance with embodiments of the present disclosure
• Figure 9 illustrates an example timing diagram illustrating hold-off and hang-over logic that may be applied on an instantaneous audio event detection signal to generate a validated audio event signal, in accordance with embodiments of the present disclosure
• Figure 10 illustrates different audio event detectors having hold-off and hang-over logic, in accordance with embodiments of the present disclosure.
• Such audio event detectors for an audio device may include a near-field detector that may detect when sounds in the near-field of the audio device is detected, such as a user of the audio device (e.g., a user that is wearing or otherwise using the audio device) speaks, a proximity detector that may detect when sounds in proximity to the audio device is detected, such as when another person in proximity to the user of the audio device speaks, and a tonal alarm detector that detects acoustic alarms that may have been originated in the vicinity of the audio device are proposed.
• Figure 1 illustrates an example of a use case scenario wherein such detectors may be used in conjunction with a playback management system to enhance a user experience, in accordance with embodiments of the present disclosure.
• Figure 2 illustrates an example playback management system that modifies a playback signal based on a decision from an event detector 2, in accordance with embodiments of the present disclosure.
• Signal processing functionality in a processor 50 may comprise an acoustic echo canceller 1 that may cancel an acoustic echo that is received at microphones 52 due to an echo coupling between an output audio transducer 51 (e.g., loudspeaker) and microphones 52.
• an output audio transducer 51 e.g., loudspeaker
• the echo reduced signal may be communicated to event detector 2 which may detect one or more various ambient events, including without limitation a near-field event (e.g., including but not limited to speech from a user of an audio device) detected by near-field detector 3, a proximity event (e.g., including but not limited to speech or other ambient sound other than near- field sound) detected by proximity detector 4, and/or a tonal alarm event detected by alarm detector 5.
• a near-field event e.g., including but not limited to speech from a user of an audio device
• proximity detector e.g., including but not limited to speech or other ambient sound other than near- field sound
• tonal alarm event detected by alarm detector 5 e.g., a tonal alarm event detected by alarm detector 5.
• an event-based playback control 6 may modify a characteristic of audio information (shown as "playback content" in Figure 2) reproduced to output audio transducer 51.
• Audio information may include any information that may be reproduced at output audio transducer 51, including without limitation, downlink speech associated with a telephonic conversation received via a communication network (e.g., a cellular network) and/or internal audio from an internal audio source (e.g., music file, video file, etc.).
• a communication network e.g., a cellular network
• internal audio from an internal audio source e.g., music file, video file, etc.
• the example event detector may comprise a voice activity detector 10, a music detector 9, a direction of arrival estimator 7, a near-field spatial information extractor 8, a background noise level estimator 11, and decision fusion logic 12 that uses information from voice activity detector 10, music detector 9, direction of arrival estimator 7, near-field spatial information extractor 8, and background noise level estimator 11 to detect audio events, including without limitation, near-field sound, proximity sound other than near- field sound, and a tonal alarm.
• Near-field detector 3 may detect near-field sounds including speech. When such near- field sound is detected, it may be desirable to modify audio information reproduced to output audio transducer 51, as detection of near- field sound may indicate that a user is participating in a conversation. Such near-field detection may need to be able to detect near-field sound in acoustically noisy conditions and be resilient to false detection of near-field sounds in very diverse background noise conditions (e.g., background noise in a restaurant, acoustical noise when driving a car, etc.). As described in greater detail below, near-field detection may require spatial sound processing using a plurality of microphones 51. In some embodiments, such near- field sound detection may be implemented in a manner identical or similar to that described in U.S. Pat. No. 8,565,446 and/or U.S. App. Ser. No. 13/199,593.
• Proximity detector 4 may detect ambient sounds (e.g., speech from a person in proximity to a user, background music, etc.) other than near-field sounds. As described in greater detail below, because it may be difficult to differentiate proximity sounds from non-stationary background noise and background music, proximity detector may utilize a music detector and noise level estimation to disable proximity detection of proximity detector 4 in order to avoid poor user experience due to false detection of proximity sounds. In some embodiments, such proximity sound detection may be implemented in a manner identical or similar to that described in U.S. Pat. No. 8,126,706, U.S. Pat. No. 8,565,446, and/or U.S. App. Ser. No. 13,199,593.
• ambient sounds e.g., speech from a person in proximity to a user, background music, etc.
• proximity detector may utilize a music detector and noise level estimation to disable proximity detection of proximity detector 4 in order to avoid poor user experience due to false detection of proximity sounds.
• such proximity sound detection may be implemented in a manner identical or similar to that described in
• Tonal alarm detector 5 may detect tonal alarms (e.g., sirens) proximate to an audio device. To provide maximum user experience, it may be desirable that tonal alarm detector 5 ignores certain alarms (e.g., feeble or low-volume alarms). As described in greater detail below, tonal alarm detection may require spatial sound processing using a plurality of microphones 51. In some embodiments, such proximity sound detection may be implemented in a manner identical or similar to that described in U.S. Pat. No. 8,126,706 and/or U.S. App. Ser. No. 13,199,593.
• tonal alarm detection may require spatial sound processing using a plurality of microphones 51. In some embodiments, such proximity sound detection may be implemented in a manner identical or similar to that described in U.S. Pat. No. 8,126,706 and/or U.S. App. Ser. No. 13,199,593.
• FIG. 4 illustrates functional blocks of a system for deriving near-field spatial statistics that may be used to detect audio events, in accordance with embodiments of the present disclosure.
• the level analysis 41 may be performed on microphones 52 by estimating the inter- microphone level difference (imd) between the near and far microphone (e.g., as described in U.S. App. Ser. No. 13/199,593).
• Cross-correlation analysis 13 may be performed on signals received by microphones 52 to obtain the direction of arrival information DOA of ambient sound that impinges on microphones 52 (e.g., as described in U.S. Pat. No. 8,565,446).
• a maximum normalized correlation value normMaxCorr may also be obtained (e.g., as described in U.S. App.
• Voice activity detector 10 may detect presence of speech and generate a signal speechDet indicative of present or absence of speech in the ambient sound (e.g., as described in the probabilistic based speech presence/absence based approach of U.S. Pat. No. 7,492,889).
• Beamformers 15 may, based on signals from microphones 52, generate a near-field signal estimate and an interference signal estimate which may be used by a noise analysis 14 to determine a level of noise noiseLevel in the ambient sound and an interference to near- field signal ratio idr.
• U.S. Pat. No. 8,565,446 describes an example approach for estimating interference to near-field signal ratio idr using a pair of beamformers 15.
• a voice activity detector 36 may use the interference estimate to detect (proxSpeechDet) any speech signal that does not originate from the desired signal direction.
• Noise analysis 14 may be performed based on the direction of arrival estimate DOA by updating interference signal energy whenever the direction of arrival estimate DOA of the ambient sound is outside the acceptance angle of the near-field sound.
• the direction of arrival of the near-field sounds may be known a priori for a given microphone array configuration in the industrial design of a personal audio device.
• Figure 5 illustrates example fusion logic for detecting near-field sound, in accordance with embodiments of the present disclosure.
• near- field speech may be detected when all the following criteria are satisfied: ⁇ Direction of arrival estimate DOA of ambient sound is within an acceptance angle of near-field sound (block 16);
• thresholds idrThres and imdTh may be dynamically adjusted based on a background noise level estimate.
• Proximity detection of proximity detector 4 may be different than near-field sound detection of near-field detector 3 because the signal characteristics of proximity speech may be very similar to ambient signals such as music and noise. Accordingly, proximity detector 4 must avoid false detection of proximity speech in order to achieve acceptable user experience. Accordingly, a music detector 9 may be used to disable proximity detection whenever there is music in the background. Similarly, proximity detector 4 may be disabled whenever background noise level is above certain threshold. The threshold value for background noise may be determined a priori such that a likelihood of false detection below the threshold level is very low.
• Figure 6 illustrates example fusion logic for detecting proximity sound (e.g. speech), in accordance with embodiments of the present disclosure. Moreover, there may exist many environment noise sources that generate acoustic stimuli that are transient in nature.
• a spectral flatness measure (SFM) statistic from the music detector 9 may be used to distinguish speech from transient noises.
• the SFM may be tracked over a period of time and the difference between the maximum and the minimum SFM value over the same duration, defined as sfmSwing may be calculated.
• the value of sfmSwing may generally be small for transient noise signals as the spectral content of these signals are wideband in nature and they tend to be stationary for a short interval of time (300-500 ms).
• the value of sfmSwing may higher for speech signals because the spectral content of speech signal may vary faster than transient signals.
• proximity sound e.g., speech
• normMaxCorrThres2 (block 22);
• the background noise level noiseLevel is below a threshold noiseLevelTh (block 23); and ⁇ Proximity voice activity is detected, as indicated by signal proxSpeechDet (block • SFM variation statistic sfmSwing is greater than a threshold sfmSwingTh (block 37);
• the music detector taught in U.S. Pat. No. 8,126,706 may be used to implement music detector 9 to detect the presence of background music.
• Another embodiment of the proximity speech detector is shown in Figure 7, in accordance with embodiments of the present disclosure. According to this embodiment, proximity speech may be detected if the following conditions are met:
• normMaxCorrThres3 (block 28);
• the following conditions may be indicative of proximity speech, in order to improve the detection rate of proximity speech without increasing occurrence of a false alarm (e.g., due to background noise conditions):
• Stationary background noise is present (block 32).
• the stationary background noise may be detected by calculating the ratio of peak-to-root mean square value of the SFM generated by music detector (block 9) over a period of time. Specifically, if the above-mentioned ratio is higher, then non- stationary noise may be present as the spectral flatness measure of a non-stationary noise tends to change faster than stationary noises;
• High noise level is present (block 32).
• the high noise-condition may be detected if the estimated background noise is greater than a threshold, noiseLevelLo and smaller than a threshold, noiseLevelHi.
• Close-talking proximity talker is present (block 33).
• a close-talking proximity talker may be detected when the maximum normalized cross -correlation statistic normMaxCorr is greater than a threshold, normMaxCorrThres4 (the threshold normMaxCorrThres4 may be greater than normMaxCorrThres3 to indicate the presence of close talker); • Low- or medium- or high-level background or no background noise is present (block 34). This condition may be detected if the estimated background noise level is less than a threshold noiseLevelThHi.
• Close-talking proximity talker is present (block 33).
• a close-talking proximity talker may be detected when the maximum normalized cross -correlation statistic normMaxCorr is greater than a threshold, normMaxCorrThres4 (the threshold normMaxCorrThres4 may be greater than normMaxCorrThres3 to indicate the presence of close talker);
• Tonal alarm detector 5 may be configured to detect alarm signals that are tonal in nature in which a sonic bandwidth of such alarm signals are also narrow (e.g., siren, buzzer).
• the tonality of an ambient sound may be measured by splitting the time domain signal into multiple sub-bands through time to frequency domain transformation and the spectral flatness measure, depicted in Figure 6 as signal sfm[] generated by music detector 9, may be computed in each sub-band.
• Spectral flatness measures sfm[] from all sub-bands may be evaluated, and a tonal alarm event may be detected if the spectrum is flat in most sub-bands but not in all sub-bands.
• near- field spatial statistics 8 of Figure 3 may be used to differentiate the far- field alarm signals from near- field signals.
• Figure 8 illustrates example fusion logic for detecting a tonal alarm event (e.g. siren, buzzer), in accordance with embodiments of the present disclosure. As shown in Figure 8, a tonal alarm event may be detected when all the following criteria are satisfied:
• FIG. 9 illustrates an example timing diagram illustrating hold-off and hang-over logic that may be applied on an instantaneous audio event detection signal to generate a validated audio event signal, in accordance with embodiments of the present disclosure.
• hold- off logic may generate a validated audio event signal in response to instantaneous detection of an audio event (e.g., near-field sound, proximity sound, tonal alarm event) being persistent for at least a predetermined time, while hang-over logic may continue to assert the validated audio event signal until the instantaneous detection of an audio event has ceased for a second predetermined time.
• an audio event e.g., near-field sound, proximity sound, tonal alarm event
• the following pseudo-code may demonstrate application of the hold-off and hang-over logic to reduce false detection of audio events, in accordance with embodiments of the present disclosure.
• holdOffCntr holdOffCntr + 1;
• hangOverCntr hangOverCntr + 1 ;
• a validated event may be further validated before generating the playback mode switching control.
• the following pseudo-code may demonstrate application of the hold-off and hang-over logic for gracefully switching between a conversational mode (e.g., in which audio information reproduced to output audio transducer 51 may be modified in response to an audio event) and a normal playback mode (e.g., in which the audio information reproduced to output audio transducer 51 is unmodified).
• Conversational Mode Enter Logic *
• timeToEnterConvModeCntr timeToEnterConvModeCntr + 1 ;
• FIG. 10 illustrates different audio event detectors having hold-off and hang-over logic, in accordance with embodiments of the present disclosure.
• the hold-off periods and/or hangover periods for each detector may be set differently.
• the playback management may be controlled differently based on the type of detected event.
• a playback gain (and hence the audio information reproduced at output audio transducer 51) may be attenuated whenever one or more of the audio events is detected.
• the smoothing parameters alpha and beta may be set at different values to adjust a gain ramping rate. It should be understood—especially by those having ordinary skill in the art with the benefit of this disclosure—that that the various operations described herein, particularly in connection with the figures, may be implemented by other circuitry or other hardware components. The order in which each operation of a given method is performed may be changed, and various elements of the systems illustrated herein may be added, reordered, combined, omitted, modified, etc. It is intended that this disclosure embrace all such modifications and changes and, accordingly, the above description should be regarded in an illustrative rather than a restrictive sense.

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