Off-head detection of in-ear headset

• US 9,894,452 B1
• Filed: 04/04/2017
• Issued: 02/13/2018
• 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:
  US15/478,681
• Time in Patent Office: 315 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. An off-head detection system for an in-ear headset, 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; 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.

2. The off-head detection system of claim 1, wherein the input device includes an active noise reduction (ANR) circuit that processes a feedback microphone signal.

3. The off-head detection system of claim 1, wherein the ANR circuit processes both the feedback and feed-forward microphone signals.

4. The off-head detection system of claim 3, wherein at least the comparison circuit is constructed and arranged as part of a digital signal processor (DSP) that compares the driver output signal, the audio signal, and the feedback and feed-forward microphone signals to determine the off-head state of the in-ear headset.

5. The off-head detection system of claim 1, further comprising a signal monitoring circuit that measures the feed-forward microphone signal and audio signal.

6. The off-head detection system of claim 5, further comprising an off-head model that processes off-head data produced according to acoustic transfer functions that change in magnitude when the device is removed from the ear.

7. The off-head detection system of claim 6, wherein the expected-output computation circuit predicts the 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 the off-head data from the off-head model, wherein when a result of the comparison confirms that the predicted driver signal is similar to a measured signal, then an off-head state is confirmed.

8. A method for performing a fit quality assessment, comprising:

detecting an off-head state when an earbud is donned;

executing an off-head detection system, wherein executing the off-head detection system comprises;

receiving by an input device an audio signal, a feed-forward microphone signal, and a driver output signal;

predicting by an expected-output computation circuit a value of the driver output signal based on a combination of the audio signal, the feed-forward microphone signal, and off-head data; and

comparing by a comparison circuit the observed output signal provided to the driver and the computed expected output to determine an off-head state of the earbud; and

displaying informational feedback regarding the off-head state.

9. The method of claim 8, further comprising measuring by a signal monitoring circuit the feed-forward microphone signal and audio signal.

10. The method of claim 8, further comprising processing by an off-head model off-head data produced according to acoustic transfer functions that change in magnitude when the device is removed from the ear.

11. The method of claim 10, further comprising predicting the 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 the off-head data from the off-head model, wherein when a result of the comparison confirms that the predicted driver signal is similar to a measured signal, then an off-head state is confirmed.

12. A method for off-head detection, comprising:

performing signal processing on a feedforward microphone signal and an input audio signal to determine an estimated discrete transform of a driver output signal;

determining an actual discrete transform of the driver output signal;

comparing the actual discrete transform and the estimated discrete transform; and

determining an off-head state when the actual discrete transform and the estimated discrete transform are determined to be sufficiently similar.

13. The method of claim 12, wherein a discrete Fourier transform (DFT) is calculated for each of the driver output signal, feed-forward microphone signal, and audio signal at select frequencies where a feedback ANR loop is active.