Off-head detection of in-ear headset

• US 10,091,597 B2
• Filed: 01/12/2018
• Issued: 10/02/2018
• Est. Priority Date: 02/24/2017
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Termeulen, Ryan, Eichfeld, Jahn Dmitri, Mier, Fernando, Sabin, Andrew
• Primary Examiner(s): Anwah, Olisa
• Application Number:
  US15/869,269
• Publication Number:
  US 20180249265A1
• Time in Patent Office: 263 Days
• CPC Class Codes: H04R 1/1016 Earpieces of the intra-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 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 2460/15 Determination of the acoustic seal of ear moulds or ear tips of hearing devices
• CPC Class Codes: H04R 25/453 electronically
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence

Abstract

An off-head detection system for an in-ear headset comprises an input device that receives an audio signal, a feed-forward microphone signal, and a driver output signal; an expected-output computation circuit that predicts a value of the driver output signal based on a combination of the audio signal and the feed-forward microphone signal from the signal monitoring circuit, and off-head data from the off-head model; and a comparison circuit that compares the observed output signal provided to the driver and the computed expected output to determine an off-head state of the in-ear headset.

Claims

1. A control system for a listening device, comprising:

a detection system that reconfigures parameters in response to a detection event;

an active noise reduction (ANR) circuit that manages at least a feedback-based noise reduction function; and

an off-head monitoring circuit that compares an actual driver output signal and a predicted driver signal to determine the detection event, the detection event including a state transition between an on-head state and an off-head state of the listening device.

2. The control system of claim 1, wherein the ANR circuit generates an anti-noise signal in response to receiving and processing a sound from an acoustic source, the anti-noise signal output to an acoustic driver for canceling ambient noise at an acoustic driver.

3. The control system of claim 1, further comprising a hearing assistance system that combines a gain with an audio signal and outputs a modified audio signal to the ANR circuit.

4. The control system of claim 3, wherein the ANR circuit includes a plurality of digital filters that receive signals detected by a feedback microphone and a feed-forward microphone respectively, and processes the detected feedback and feed-forward microphone signals and the modified audio signal from the hearing assistance system to generate an output signal to an acoustic driver.

5. The control system of claim 1, further comprising a gain reduction system that reduces oscillation when the listening device is removed from an ear.

6. The control system of claim 1, wherein the off-head monitoring circuit detects when the listening device is taken off-head by comparing a current state of the detection system and an expected state of the detection system.

7. The control system of claim 6, wherein the off-head monitoring circuit comprises:

a signal monitoring circuit that measures a feed-forward microphone input and an audio input to the ANR circuit;

an off-head model that processes off-head data produced according to acoustic transfer functions that change in magnitude when the listening device is removed from an ear in the off-head state of the listening device;

an expected-output computation circuit that predicts a value of an output of the ANR circuit based on a combination of the measured feed-forward microphone input, the measured audio input, and values corresponding to the acoustic transfer functions stored in the off-head model; and

a comparator that compares a combination of the output of the ANR circuit, the audio input signal, and the feed-forward microphone input to determine the off-head state of the state transition of the listening device.

8. The control system of claim 7, the comparison circuit is constructed and arranged as part of a digital signal processor (DSP) that compares the output of the ANR circuit, the audio input signal, and the feed-forward microphone input, in addition to a feedback microphone input from a feedback microphone to determine the off-head state of the listening device.

9. The control system of claim 7, wherein the expected-output computation circuit predicts the value of the output signal based on a combination of the audio signal and the feed-forward microphone signal and the off-head data, wherein when a result of the comparison confirms that the predicted driver signal is similar to a measured signal, then the off-head state is confirmed.

10. A system for performing a fit quality assessment, comprising:

an input device that receives an audio signal, a feed-forward microphone signal, and a driver output signal;

an expected-output computation circuit that predicts a value of the driver output signal based on a combination of the audio signal, the feed-forward microphone signal, and off-head data produced according to acoustic transfer functions that change in magnitude when the headset is removed from an ear in an off-head state of the headset;

a comparison circuit that compares the driver output signal, the audio signal, and the feed-forward microphone signals to determine the off-head state of the headset; and

a display that displays informational feedback regarding the off-head state.

11. The system of claim 10, wherein the input device comprises an active noise reduction (ANR) circuit that processes a feedback microphone signal.

12. The system of claim 11, wherein the comparison circuit is constructed and arranged as part of a digital signal processor (DSP) that compares the driver output signal, the audio signal, the feedback microphone signal and the feed-forward microphone signal to determine the off-head state of the headset.

13. The system of claim 10, further comprising a gain reduction system that reduces oscillation when the headset is removed from an ear.

14. The system of claim 10, wherein when the off-head state is confirmed, the headset is configured to automatically power-down after expiration of a timer.

15. The system of claim 10, wherein when an off-head state is confirmed, the headset is configured to automatically transition into a different power state after expiration of a timer.

16. The system of claim 10, wherein the display comprises a use-interface to display an indication of the off-head state of the headset.

18. The system of claim 16, wherein the detection system calculates a discrete Fourier transform (DFT) for each of the driver output signal, feed-forward microphone signal, and audio signal at select frequencies where a feedback ANR loop is active.

17. A system for off-head detection, comprising:

a detection system that performs signal processing on a feedforward microphone signal and an input audio signal to determine an estimated discrete transform of a driver output signal;

a processor of the detection system that determines an actual discrete transform of the driver output signal; and

a comparison circuit that compares the actual discrete transform and the estimated discrete transform and determines an off-head state when the actual discrete transform and the estimated discrete transform are determined to be sufficiently similar.