Method of detecting silence in a packetized voice stream

• US 6,535,844 B1
• Filed: 05/30/2000
• Issued: 03/18/2003
• Est. Priority Date: 05/28/1999
• Status: Expired due to Fees

• Current Assignee: Zarlink Semiconductor Inc. (Microchip Technology Incorporated)
• Original Assignee: Zarlink Semiconductor Inc. (Microchip Technology Incorporated)
• Inventors: Beaucoup, Franck, Wood, Robert Geoffrey
• Primary Examiner(s): MCFADDEN, SUSAN IRIS
• Application Number:
  US09/580,788
• Time in Patent Office: 1,022 Days
• Field of Search: 764/210, 764/213, 764/215, 764/219, 764/226, 764/208, 764/220, 764/222, 764/223
• US Class Current: 704/210
• 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

A method and apparatus for detecting silence in voice packets. A packet energy calculator calculates a smoothed energy value for each packet of voice data to be transmitted. A noise level detector adaptively calculates noise values during periods of said silence. A silent packet detector compares the energy value to the noise value and if it is less than the noise value and less than a predetermined silence ceiling value then silence is indicated. Also, if the energy value is less than a predetermined silence noise value then silence is also indicated.

Claims

1. A method of detecting silence in a packetized voice communication system, comprising the steps of:

calculating a total energy value FE_n for each packet of voice and calculating therefrom a smoothed energy value SE_n as follows;

2. The method of claim 1, wherein A=B=0.5.

3. The method of claim 1, wherein A=0.75 and B=0.25.

4. The method of claim 1, wherein said step of calculating said noise value comprises the further steps of calculating a nosie level NL as follows:

5. The method of claim 1, further comprising the step of counting a predetermined number of consecutive packets containing silence before indicating said detection of silence, thereby permitting fricatives to be transmitted.

6. A silence detector for inhibiting transmission of silence packets by a network transmitter, comprising:

a packet energy calculator for calculating an energy value SE_n for each packet of voice data to be transmitted, wherein said packet energy calculator further comprises an expander for generating sample energy values, an accumulator for summing said sample energy values for each packet thereby resulting in a total packet energy value FE_n and circuitry for receiving said total packet energy value FE_n and in response generating a smoothed energy value SE_n, as follows;

7. The silence detector of claim 6, further comprising a silence duration monitor for counting a predetermined number of consecutive packets containing silence and thereafter generating a signal for inhibiting said transmitter.

8. The silence detector of claim 6, wherein A=B=0.5.

9. The silence detector of claim 6, wherein A=0.75 and B=0.25.

10. The silence detector of claim 6, wherein said noise level detector generates said noise level as follows: