HEARING AID WITH HISTOGRAM BASED SOUND ENVIRONMENT CLASSIFICATION

• US 20100027820A1
• Filed: 09/04/2007
• Published: 02/04/2010
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: GN Resound A/S (GN Store Nord A/S)
• Original Assignee: GN Resound A/S (GN Store Nord A/S)
• Inventors: Kates, James Mitchell
• Granted Patent: US 8,948,428 B2
• Time in Patent Office: Days
• US Class Current: 381/312
• CPC Class Codes: G10L 2025/783 based on threshold decision
• CPC Class Codes: G10L 25/00 Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 muting semiconductor-based amplifiers when some special characteristics of a signal are sensed by a speech detector, e.g. sensing when no signal is present, H03G3/34
• CPC Class Codes: H04R 2225/41 Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest
• CPC Class Codes: H04R 2430/03 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/507 implemented by neural network or fuzzy logic

Abstract

The present invention relates to an alternative method of classifying the sound environment into a number of environmental classes, such as speech, babble speech, restaurant clatter music, traffic noise, etc., based on signal level histogram values in a number of frequency bands.

Claims

1. A hearing aid comprising

a microphone and an A/D converter for provision of a digital input signal in response to sound signals received at the respective microphone in a sound environment,

a processor that is adapted to process the digital input signals in accordance with a predetermined signal processing algorithm to generate a processed output signal, and

a sound environment detector for determination of the sound environment of the hearing aid based on the digital input signal and providing an output for selection of the signal processing algorithm generating the processed output signal, the sound environment detector including

a feature extractor for determination of histogram values of the digital input signal in a plurality of frequency bands,

an environment classifier adapted for classifying the sound environment into a number of environmental classes based on the determined histogram values from at least two frequency bands, and

a parameter map for the provision of the output for selection of the signal processing algorithm, and

a D/A converter and an output transducer for conversion of the respective processed sound signal to an acoustic output signal.

2. A hearing aid according to claim 1, wherein the feature extractor is adapted to determine histograms in a plurality of frequency warped frequency bands.

3. A hearing aid according to claim 1 or 2, wherein the feature extractor is adapted to determine histograms of the digital input signal level.

4. A hearing aid according to claim 1 or 2, wherein the feature extractor is adapted to determine histograms of the logarithmic digital input signal level.

5. A hearing aid according to any of the previous claims, wherein processed histogram values are input to the environment classifier.

6. A hearing aid according to any of the previous claims, wherein normalized histogram values are input to the environment classifier.

7. A hearing aid according to any of the previous claims, wherein the histogram values input to the environment classifier represent the time during which the signal levels reside within a corresponding signal level range.

8. A hearing aid according to any of the preceding claims, wherein the environment classifier comprises at least one element selected from the group consisting of a neural network, a hidden Markov Model, a Bayesian classifier, a nearest neighbour classifier, a support vector machine, and a relevance vector machine.

9. A hearing aid according to claim 7 or 8, wherein the environment classifier is trained with a combination of signals from different signal classes.

10. A hearing aid according to any of the previous claims, wherein the environment classifier classifies the sound environment based on histogram values as a function of frequency.

11. A hearing aid according to any of the previous claims, wherein the environment classifier classifies the sound environment based on histogram values in selected frequency bands.

12. A hearing aid according to any of the previous claims, wherein the environment classifier classifies the sound environment based on histogram values in combination with at least one other signal parameter.

13. A hearing aid according to claim 12, wherein the at least one other signal parameter is selected from the group consisting of the zero-crossing rate, delta zero crossing rate, higher moments of zero crossing rate, mel cepstrum coefficients, delta cepstrum coefficients, harmonics content, flatness, crest factor, tonality, spectral envelope, block energy, on-offset times, silence ratio, amplitude histogram, autocorrelation, pitch, delta pitch, and variance.

14. A hearing aid according to any of the previous claims, wherein the feature extractor is further adapted for envelope modulation detection and to input envelope modulation features to the environment classifier.

15. A hearing aid according to any of the previous claims, wherein the environment classifier is adapted for classification based on at least four histogram bin values from at least two frequency bands.

16. A hearing aid according to any of the previous claims, wherein the environment classifier is adapted for determining the strongest part of sound signals.

17. A hearing aid according to any of the previous claims, wherein the environment classifier is adapted for determining a weaker part than the strongest part of sound signals.

18. A hearing aid according to any of the previous claims, wherein the environment classifier classifies the sound environment based on at least one parameter derived from determined histogram values.

19. A hearing aid according to claim 18, wherein the at least one parameter is selected from the group of parameters consisting of the median, the mean, and the standard deviation of determined histogram values.