METHOD FOR DETECTING AUDIO TICKS IN A NOISY ENVIRONMENT

• US 20120288103A1
• Filed: 11/26/2010
• Published: 11/15/2012
• Est. Priority Date: 11/27/2009
• Status: Active Grant

• Current Assignee: K.Mizra LLC
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Klos, Victor Bastiaan, van Staalduinen, Mark, Doets, Peter Jan Otto
• Granted Patent: US 9,235,259 B2
• Time in Patent Office: Days
• US Class Current: 381/56
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 2200/1636 Sensing arrangement for detection of a tap gesture on the housing
• CPC Class Codes: G06F 3/002 Specific input/output arrangements not covered by G06F3/01 - G06F3/16 other optical apparatus G02B27/00
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: G10L 25/48 specially adapted for particular use

Abstract

A method for detecting, in an audio signal including a stream of audio samples (y(n), (y′(n)), ticks in a noisy environment, comprises the steps of applying the signal to a coarse tick detection processor arranged to decide whether it is likely that the signal includes a tick and, only then, enabling a fine tick detection processor to decide, by more thorough processing the audio signal, whether the audio signal represents an audio tick. The coarse processing step preferably includes buffering audio samples (y(n), (y′(n)), determining the maximum and minimum values of each sample, forming their local range, delaying the local range with one or more samples and comparing the difference between the actual local range and the delayed local range with a threshold value (T_c), and, if the difference exceeds the threshold value, outputting a trigger (n_c) for enabling the fine detection processor The fine processing step preferably includes buffering audio samples (y(n), (y′(n)), computing, for each buffer content (B_p(n,m)), a Fast Fourier Transformed buffer content (E_c(ω,m)), determining the difference (F_c(ω,m)) between the resulting frequency components, comparing the difference (F_c(ω,m)) to the content of a previously trained fingerprint set (F*(ω,m)) and calculating a correlation coefficient (p(F_c,F*)) between them, comparing the correlation coefficient to a threshold value (T_p) and, if the correlation coefficient exceeds the threshold value, outputting a signal indication the presence of a tick in the audio signal.

Claims

1. Method for detecting ticks in a noisy environment, from an audio signal which includes a stream of audio samples (y(n), (y′

(n)), the method comprising the steps of;

applying the audio signal to a coarse tick detection processor arranged to decide whether it is likely that the audio signal includes a tick and, only then,

enabling a fine tick detection processor to decide, by more thorough processing said audio signal, whether the audio signal represents a tick.

2. Method according claim 1, wherein the stream of audio samples is derived from a microphone of a mobile communication device that captures sound generated by tapping the mobile communication device against other objects and noise from an environment of the mobile communication device.

3. Method according claim 1, wherein the fine tick detection is performed using a comparison with predetermined reference properties that are characteristic for a specific device with which the audio signal is received.

4. Method according claim 3, wherein said comparison comprises computing a correlation coefficient between the reference properties and information derived from the stream of audio samples.

5. Method according claim 1, wherein the coarse processing step includes buffering audio samples (y(n), (y′

(n)), determining the maximum and minimum values of each sample, forming their local range, delaying said local range with one or more samples, and comparing the difference between the actual local range and the delayed local range with a threshold value (T_c), and, if the difference exceeds the threshold value, outputting a trigger (n_c) for enabling said fine detection processor.

6. Method according to claim 1, wherein the fine processing step includes buffering audio samples (y(n), (y′

(n)), computing, for each buffer content (B_p(n,m)), a Fast Fourier Transformed buffer content (E_c(w,m)), determining the difference (F_c(w,m)) between the resulting frequency components, comparing said difference (F_c(w,m)) to the content of a previously trained reference set (F*(w,m)) and calculating a correlation coefficient (ρ

(F_c,F*)) between them, comparing said correlation coefficient to a threshold value (T_p) and, if the correlation coefficient exceeds the threshold value, outputting a signal indication the presence of a tick in the audio signal.

7. Method according to claim 6, comprising a training step, wherein the reference set of a touch is formed that is specific for a mobile device from which the stream of audio samples is derived using a microphone of a mobile communication device.

8. Method according to claim 1, wherein the audio signal is preprocessed before being processed in the coarse and/or fine processing steps respectively, including determining and outputting a difference (y′

(n)) between each audio sample (y(n)) and a previous audio sample (y(n−

x)).

9. A computer program product comprising a program of instructions for making a programmable computer to carry out one or more of the method steps according to claim 1.

17. Consumer product, adapted for carrying out the method according to claim 1, and/or comprising a system according to claim 10.

18. Consumer product according to claim 17, which is a mobile telephone device or a PDA.

19. Server for identifying proximate devices, adapted for carrying out the method according to claim 1 and/or comprising a system according to claim 10.

10. System for detecting, in an audio signal which includes a stream of audio samples (y(n), (y′

(n)), ticks in a noisy environment, the system comprising a coarse tick detection processor and a fine tick processor, wherein the course tick processor is arranged to decide whether it is likely that the signal includes a tick and, only then, to enable the fine tick detection processor to decide, by more thorough processing of said audio signal, whether the audio signal represents a tick.

11. System according claim 10, comprising a mobile telecommunication device comprising a microphone, coupled to the coarse tick detection processor and a fine tick processor to supply the stream of audio samples.

12. System according claim 10, wherein the fine tick detection processor is configured to perform a comparison with predetermined reference properties that are characteristic for a specific device with which the audio signal is received.

13. System according to claim 10, wherein the coarse tick processor is adapted for buffering audio samples (y(n), (y′

(n)), for determining the maximum and minimum values of each sample, forming their local range, for delaying said local range with one or more samples and for comparing the difference between the actual local range and the delayed local range with a threshold value (T_c), and for, if the difference exceeds the threshold value, outputting a trigger (n_c) for enabling said fine detection processor

14. System according to claim 10, wherein the fine tick processor is adapted for buffering audio samples (y(n), (y′

(n)), for computing, for each buffer content (B_p(n,m)), a Fast Fourier Transformed buffer content (E_c(w,m)), for determining the difference (F_c(w,m)) between the resulting frequency components, for comparing said difference (F_c(w,m)) to the content of a previously trained reference set (F*(w,m)) and calculating a correlation coefficient (ρ

(F_c, F*)) between them, for comparing said correlation coefficient to a threshold value (T_p) and for, if the correlation coefficient exceeds the threshold value, outputting a signal indication the presence of a tick in the audio signal.

15. System according to claim 10, including a preprocessor adapted for preprocessing the audio signal before being processed in the coarse and/or fine processors respectively, the preprocessor being arranged for determining and outputting a difference (y′

(n)) between each audio sample (y(n)) and a previous audio sample (y(n−

x)).

16. System according to claim 10, comprising a mobile communication device with a microphone coupled to the coarse tick detection processor and the fine tick processor, the fine tick processor being configured to trigger mutual identification of, or opening of a communication channel between, a pair of mobile communication devices that includes the mobile communication device, in response to fine tick detection.