AUDIO HEADSET WITH ACTIVE NOISE CONTROL, ANTI-OCCLUSION CONTROL AND PASSIVE ATTENUATION CANCELLING, AS A FUNCTION OF THE PRESENCE OR THE ABSENCE OF A VOICE ACTIVITY OF THE HEADSET USER

• US 20170148428A1
• Filed: 10/24/2016
• Published: 05/25/2017
• Est. Priority Date: 11/19/2015
• Status: Abandoned Application

• Current Assignee: Parrot Drones
• Original Assignee: Parrot Drones
• Inventors: Thuy, Vu Hoang Co, Michau, Marc, Poncot, Remi
• Application Number:
  US15/332,888
• Publication Number:
  US 20170148428A1
• Time in Patent Office: Days
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17861 using additional means for damping sound, e.g. using sound absorbing panels
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3016 Control strategies, e.g. energy minimization or intensity measurements
• CPC Class Codes: G10K 2210/3026 Feedback
• CPC Class Codes: G10K 2210/3027 Feedforward
• CPC Class Codes: G10K 2210/3028 Filtering, e.g. Kalman filters or special analogue or digital filters
• CPC Class Codes: G10K 2210/3221 Headrests, seats or the like, for personal ANC systems
• CPC Class Codes: G10K 2210/3224 Passive absorbers
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04R 1/1008 Earpieces of the supra-aural or circum-aural type
• CPC Class Codes: H04R 1/1041 Mechanical or electronic switches, or control elements switches in general H01H
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06
• CPC Class Codes: H04R 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 2460/05 Electronic compensation of the occlusion effect

Abstract

The headset includes an active noise control with an internal microphone (28) and an external microphone (32). A processor (42) comprises a feedback branch (46), adjusted so as to attenuate the low frequencies corresponding to a component of a voice signal transmitted by bone conduction, and a feedforward branch (58) adjusted so as to compensate for the attenuation introduced by the feedback filtering and the passive acoustic attenuation introduced between the outside and the inside of the headset. A voice activity detector (60) operates a dynamic switching between two couples (H_FB, H_FF) of different transfer functions applied to the feedback (46) and feedforward (58) functions. This allows rendering in the most natural way possible to the user all the external sounds, including his own voice.

Claims

1. An audio headset, comprising two earphones (10) each including a transducer (18) for sound reproduction of an audio signal to be reproduced, this transducer being housed in an ear acoustic cavity (22), this headset comprising an active noise control system with:

an internal microphone (28), placed inside the acoustic cavity (22) and adapted to deliver a first signal (e);

an external microphone (32), placed outside the acoustic cavity (22) and adapted to deliver a second signal, and

a digital signal processor (42), comprising;

a closed-loop feedback branch (30), comprising a feedback filter (46) adapted to apply a feedback filtering transfer function H_FB to said first signal delivered by the internal microphone (28);

an open-loop feedforward branch (34), comprising a feedforward filter (58) adapted to apply a feedforward filtering transfer function H_FF to said second signal delivered by the external microphone (32); and

mixing means (54), receiving as an input the signal delivered by the feedback branch at the exit of the feedback filter (46) and by the feedforward branch at the exit of the feedforward filter (58), as well as a possible audio signal to be reproduced (M), and delivering as an output a signal adapted to pilot the transducer (18),

this audio headset further comprising means adapted to operate an anti-occlusion control and a cancellation of the passive attenuation introduced by the headset, comprising;

means (60) for detecting the voice activity of the headset user, adapted to discriminate between a situation of presence and a situation of absence of voice activity of the headset user; and

means (60) for dynamic switching, selectively as a function of the current result of the voice activity detection, between two couples of different transfer functions {H_FB,H_FF} applied to the feedback (46) and feedforward (58) filters,

characterized in that;

in the absence of voice activity, the parameters of the feedforward filtering transfer function (H_FF2) applied to the feedforward filter (58) by the dynamic switching means to operate said cancellation of the passive attenuation are chosen so as to provide, in a range of frequencies comprised at least between 100 and 300 Hz, a first feedforward filtering gain lower than a second feedforward filtering gain of the feedforward filtering transfer function (H_FF1) applied to the feedforward filter (58) by the dynamic switching means to operate said anti-occlusion control in the presence of voice activity, and

in the presence of vocal activity, the parameters of the feedback filtering transfer function (H_FB1) applied to the feedback filter (46) by the dynamic switching means to operate said anti-occlusion control are chosen so as to provide, in a range of frequencies comprised at least between 100 and 300 Hz, a first feedback filtering gain higher than a second feedback filtering gain of the feedback filtering transfer function (H_FB2) applied to the feedback filter (46) by the dynamic switching means in the absence of voice activity.

2. The headset of claim 1, wherein said first feedforward filtering gain in the absence of voice activity is of at most 8 dB for the frequencies below 1 kHz.

3. The headset of claim 1, wherein said second feedforward filtering gain in the presence of voice activity is of at least 10 dB in a range of frequencies comprised at least between 100 and 300 Hz.

4. The headset of claim 1, wherein said first feedback filtering gain in the presence of voice activity is of at least 15 dB in a range of frequencies comprised at least between 100 and 300 Hz.

5. The headset of claim 1, wherein said second feedback gain in the absence of voice activity is of at most 5 dB for the frequencies comprised between 200 Hz and 1 kHz.

6. The headset of claim 1, wherein the parameters of the feedforward (H_FF2) and feedback (H_FB2) filtering transfer functions applied by the dynamic switching means to the feedforward (58) and feedback (46) filters in the absence of voice activity are chosen so as to provide together, for the frequencies below 1 kHz, a hiss lower than that provided by the feedforward (H_FF1) and feedback (H_FB1) filtering transfer functions applied by the dynamic switching means in the presence of voice activity.

7. The headset of claim 6, wherein the parameters of the feedforward (H_FF1) and feedback (H_FB1) filtering transfer functions applied by the dynamic switching means to the feedforward (58) and feedback (46) filters in the presence of voice activity are chosen so as to provide together, for the frequencies below 1 kHz, a final restitution of the external noise close to that provided by the feedforward (H_FF2) and feedback (H_FB2) filtering transfer functions applied by the dynamic switching means in the absence of voice activity, so as to avoid an audible discontinuity upon a switching.

8. The headset of claim 1, wherein:

the feedforward filter (58) is one between a plurality of selectively switchable preconfigured feedforward filters; and

the digital signal processor (42) further comprises;

means (64) for analysing said first signal (e) delivered by the internal microphone (28), adapted to verify whether or not current characteristics of this first signal verify a set of predetermined criteria; and

selection means (70), adapted to select one of the preconfigured feedforward filters as a function of the result of the verification of the first set of criteria performed by the analysis means on the characteristics of the first signal (28).

9. The audio headset of claim 8, wherein the current characteristics of the first signal comprise values of energy of this first signal (Rms1, Rms2, . . . ) in a plurality of bands of frequencies (Filtre1, Filtre2, . . . ), and the predetermined criteria comprise a series of respective thresholds (Seuil(1,1), Seuil(2, 1), . . . ) with which are compared said values of energy.

10. The audio headset of claim 9, wherein:

the set of predetermined criteria further comprises a criterion of presence or not of an audio signal (M) to be reproduced; and

two different series of said respective thresholds are provided, with which are compared said values of energy, one or the other of these two series being selected (74, 74′

) according to whether an audio signal to be reproduced is present or not.