VAD Detection Apparatus and Method of Operating the Same

• US 20150120299A1
• Filed: 10/28/2014
• Published: 04/30/2015
• Est. Priority Date: 10/29/2013
• Status: Active Grant

• Current Assignee: Knowles Electronics Llc (Knowles Corporation)
• Original Assignee: Knowles Electronics Llc (Knowles Corporation)
• Inventors: Thomsen, Henrik, Nandy, Dibyendu
• Granted Patent: US 9,147,397 B2
• Time in Patent Office: Days
• US Class Current: 704/246
• CPC Class Codes: G10L 15/08 Speech classification or search
• CPC Class Codes: G10L 15/22 Procedures used during a speech recognition process, e.g. man-machine dialogue
• CPC Class Codes: G10L 17/02 Preprocessing operations, e.g. segment selection; Pattern representation or modelling, e.g. based on linear discriminant analysis [LDA] or principal components; Feature selection or extraction
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 2015/088 Word spotting
• CPC Class Codes: G10L 25/21 the extracted parameters being power information
• 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 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04W 4/16 Communication-related supplementary services, e.g. call-transfer or call-hold

Abstract

At a processing device, a first signal from a first microphone and a second signal from a second microphone are received. The first signal indicates whether a voice signal has been determined at the first microphone, and the second signal indicates whether a voice signal has been determined at the second microphone. When the first signal indicates potential voice activity or the second signal indicates potential voice activity, the processing device is activated to receive data and the data is examined for a trigger word. When the trigger word is found, a signal is sent to an application processor to further process information from one or more of the first microphone and the second microphone. When no trigger word is found, the processing device is reset to deactivate data input and allowing the first microphone and the second microphone to enter or maintain an event detection mode of operation.

Claims

1. A method, comprising:

at a processing device, receiving a first signal from a first microphone and a second signal from a second microphone, the first signal indicating whether a voice signal has been determined at the first microphone, and the second signal indicating whether a voice signal has been determined at the second microphone;

when the first signal indicates potential voice activity or the second signal indicates potential voice activity, activating the processing device to receive data and subsequently examining the data for a trigger word and when the trigger word is found, sending a signal to an application processor to further process information from one or more of the first microphone and the second microphone;

when no trigger word is found, resetting the processing device to deactivate data input and allowing the first microphone and the second microphone to enter or maintain an event detection mode of operation.

2. The method of claim 1, further comprising wherein the application processor utilizes a voice recognition (VR) module to determine whether other or further commands can be recognized in the information.

3. The method of claim 1 wherein the first microphone and the second microphone transmit pulse density modulation (PDM) data.

4. The method of claim 1, wherein the first microphone includes a first voice activity detection (VAD) module that determines whether voice activity has been detected, and the second microphone includes a second voice activity detection (VAD) module that determines whether voice activity has been detected.

5. The method of claim 4, wherein the first VAD and the second VAD module perform the steps of:

receiving a sound energy from a source;

filtering the sound energy into a plurality of filter bands;

obtaining a power estimate for each of the plurality of filter bands; and

based upon each power estimate, determining whether voice activity is detected.

6. The method of claim 5, wherein the filtering utilizes one or more low pass filters, high pass filters, and frequency dividers.

7. The method of claim 5, wherein the power estimate comprises an upper power estimate and a lower power estimate.

8. The method of claim 4, wherein either the first VAD module or the second VAD module performs Trigger Phrase recognition.

9. The method of claim 4, wherein either the first VAD module or the second VAD module performs Command Recognition.

10. The method of claim 1, wherein the processing device controls the first microphone and the second microphone by varying a clock frequency of a clock supplied to the first microphone and the second microphone.

14. The system of claim 10, wherein the processing device controls the first microphone and the second microphone by varying a clock frequency of a clock supplied to the first microphone and the second microphone.

11. A system, the system comprising:

a first microphone with a first voice activity detection (VAD) module;

a second microphone with a second voice activity detection (VAD) module;

a processing device communicatively coupled to the first microphone and the second microphone, the processing device configured to receive a first signal from the first microphone and a second signal from the second microphone, the first signal indicating whether a voice signal has been determined at the first microphone by the first VAD module, and the second signal indicating whether a voice signal has been determined at the second microphone by the second VAD module, the processing device further configured to when the first signal indicates potential voice activity or the second signal indicates potential voice activity, activate and receive data from the first microphone or the second microphone, and subsequently examine the data for a trigger word, and when the trigger word is found, send a signal to an application processor to further process information from one or more of the first microphone and the second microphone, the processing device further configured to when no trigger word is found, transmit a third signal to the first microphone and the second microphone, the third signal causing the first microphone and second microphone to enter or maintain an event detection mode of operation.

12. The system of claim 11, wherein either the first VAD module or the second VAD module performs Trigger Phrase recognition.

13. The system of claim 11, wherein either the first VAD module or the second VAD module performs Command Recognition.

15. A method detecting voice activity in a micro-electro-mechanical system (MEMS) microphone, the method comprising:

receiving a sound energy from a source;

filtering the sound energy into a plurality of filter bands;

obtaining a power estimate for each of the plurality of filter bands;

based upon each power estimate, determining whether voice activity is detected.

16. The method of claim 15, wherein the filtering utilizes one or more low pass filters, high pass filters and frequency dividers.

17. The method of claim 15, wherein the power estimate comprises an upper power estimate and a lower power estimate.

18. The method of claim 17, wherein ratios between the upper power estimate and the lower power estimate within the plurality of filter bands are determined, and selected ones of the ratios are compared to a predetermined threshold.

19. The method of claim 17, wherein ratios between the upper power estimate and the lower power estimate between the plurality of filter bands are determined, and selected ones of the ratios are compared to a predetermined threshold.