Apparatus and method for voice activity detection

• US 20050154583A1
• Filed: 12/23/2004
• Published: 07/14/2005
• Est. Priority Date: 12/25/2003
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Ohya, Tomoyuki, Naka, Nobuhiko
• Granted Patent: US 8,442,817 B2
• Time in Patent Office: Days
• US Class Current: 704/217
• CPC Class Codes: G10L 25/06 the extracted parameters being correlation coefficients
• 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

Abstract

It is provided a voice activity decision apparatus capable of accurately performing the decision on the state being associated with a sound interval or a silence interval also in terms of the input signal having many aperiodic components and/or plural mixed different periodic components. The apparatus 1 comprises: an autocorrelation calculating unit 11 for calculating autocorrelation values of an input signal; a delay calculating unit 12 for calculating plural delays at which autocorrelation values calculated by the autocorrelation calculating unit 11 become maximums; a noise deciding unit 13 for deciding whether the input signal is a noise or not based on the plurality of delays calculated by the delay calculating unit 12; and an activity decision unit 14 for performing the activity decision in terms of the input signal based on results of decision by the noise deciding unit 13 and the input signal.

Claims

1. A voice activity decision apparatus comprising:

an autocorrelation calculating means for calculating autocorrelation values of an input signal;

a delay calculating means for calculating a plurality of delays at which autocorrelation values calculated by said autocorrelation calculating means become maximums;

a characteristic deciding means for deciding a characteristic of said input signal on the basis of said plurality of delays calculated by said delay calculating means; and

an activity decision means for performing the decision for the activity in terms of the input signal on the basis of the result of decision by said characteristic deciding means.

2. A voice activity decision apparatus according to claim 1, wherein said activity decision means performs the decision for the activity in terms of the input signal on the basis of the result of decision by said characteristic deciding means as well as said input signal.

3. A voice activity decision apparatus according to claim 1, further comprising a noise estimating means for estimating a noise from said input signal, wherein the decision by said activity decision means is adapted on the basis of the result of decision by said characteristic deciding means, said input signal, and a noise estimated by said noise estimating means.

4. An activity decision apparatus according to claim 3, wherein said noise estimating means changes the method of estimating a noise, based on the result of decision by said activity decision means.

5. An activity decision apparatus according to claim 1, wherein said delay calculating means calculates said plurality of delays in order of the magnitude in terms of autocorrelation value.

6. An activity decision apparatus according to claim 1, wherein said delay calculating means divides a delay-observation interval into a plurality of intervals and calculates a delay for each of said plurality of intervals, where the autocorrelation value becomes the largest.

7. An activity decision apparatus according to claim 6, wherein said plurality of intervals are represented by 2^i-1·

min_t to 2ⁱ·

min_t (i;

natural number) where min_t is the shortest delay of said delay-observation interval.

8. A voice activity decision method comprising:

an autocorrelation calculating step of calculating autocorrelation values of an input signal;

a delay calculating step of calculating a plurality of delays at which autocorrelation values calculated by said autocorrelation calculating step become maximums;

a characteristic deciding step of deciding a characteristic of said input signal on the basis of said plurality of delays calculated in said delay calculating step; and

an activity decision step of deciding the activity of said input signal on the basis of the result of decision in said characteristic deciding step.