Speech signal transmitting and receiving apparatus with noise sensitive volume control

• US 5,732,390 A
• Filed: 08/12/1996
• Issued: 03/24/1998
• Est. Priority Date: 06/29/1993
• Status: Expired due to Term

• Current Assignee: Ironworks Patents LLC
• Original Assignee: Keiichi Katayanagi, Kentaro Odaka, Masayuki Nishiguchi
• Inventors: Katayanagi, Keiichi, Odaka, Kentaro, Nishiguchi, Masayuki
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): COLLINS, ALPHONSO
• Application Number:
  US08/695,522
• Time in Patent Office: 589 Days
• Field of Search: 395/2.34-2.37, 395/2.31, 395/2.32, 395/2.42
• US Class Current: 704/227
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• 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: G10L 25/84 for discriminating voice from noise

Abstract

A speech signal transmitting receiving apparatus, such as a portable telephone set, includes a speech signal transmitting encoding circuit, a noise domain detection unit, a noise level detection unit and a controller. The speech signal transmitting encoding circuit compresses input speech signals by digital signal processing at a high efficiency. The noise domain detection unit detects the noise domain using an analytic pattern produced by the speech signal transmitting encoding circuit. The noise level detection unit detects the noise level of the noise domain detected by the noise domain detection unit. The controller controls the received sound volume responsive to the noise level detected by the noise level detection unit.

Claims

1. A speech signal transmitting and receiving apparatus comprising:

a speech signal encoder for compressing input speech signals by digital signal processing for high quality voice transmission at a low bit rate and for producing patterns of analytic parameters from the input speech signal;

a transmitting and receiving circuit for transmitting the compressed speech signals output by said speech signal encoder and for receiving compressed speech signals transmitted from another transmitter and reproducing a corresponding received sound;

noise domain detection means supplied with patterns of analytic parameters produced by said speech signal encoder during compression of the input speech signals for determining a noise domain in which only noise exists in the input speech signal;

noise level detecting means for detecting a noise level of the input speech signal in the noise domain; and

means for controlling a volume of the corresponding received sound responsive to the noise level detected by said noise domain detection means.

2. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means employs a first-order linear prediction encoding coefficient as one of the analytic parameters for each frame of a plurality of frames and deems a frame to be the noise domain if the first-order linear prediction encoding coefficient is smaller than a pre-set threshold.

3. The speech signal transmitting and receiving apparatus as claimed in claim 2 wherein said noise domain detection means employs a pitch gain indicating the intensity of pitch components as one of the analytic parameters for each frame and deems a frame to be the noise domain if the pitch gain is within a preset range.

4. The speech signal transmitting and receiving apparatus as claimed in claim 3 wherein said noise domain detection means employs a pitch lag as one of the analytic parameters for each frame and deems a frame to be the noise domain if the pitch lag is zero.

5. The speech signal transmitting and receiving apparatus as claimed in claim 4 wherein said noise domain detection means employs a frame power as one of the analytic parameters for each frame and deems a particular frame to be the noise domain if the frame power for the particular frame is smaller than a pre-set threshold.

6. The speech signal transmitting and receiving apparatus as claimed in claim 5 wherein, if an amount of change of the frame power between a current frame and a past frame exceeds a pre-set threshold, said noise domain detection means deems said current frame to be a speech domain, even if said current domain is the noise domain.

7. The speech signal transmitting and receiving apparatus as claimed in claim 6 wherein said noise domain detection means detects the noise domain in view of the value of the analytic parameters over plural consecutive frames.

8. The speech signal transmitting and receiving apparatus as claimed in claim 7 wherein said noise level detection means performs filtering on a noise level output of the noise domain detected by said noise domain detection means.

9. The speech signal transmitting and receiving apparatus as claimed in claim 8 wherein the filtering performed by said noise level detection means on the noise level output is minimum value filtering.

10. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means employs a pitch gain indicating the intensity of pitch components as one of the analytic parameters for each frame of a plurality of frames and deems a frame to be the noise domain if the pitch gain is within a pre-set range.

11. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means employs a pitch lag as one of the analytic parameters for each frame of a plurality of frames and deems a frame to be the noise domain if the pitch lag is zero.

12. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means employs a frame power as one of the analytic parameters for each frame of a plurality of frames and deems a frame to be the noise domain if the frame power for said one frame is smaller than a pre-set threshold.

13. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means employs a frame power as one of the analytic parameters for each frame of a plurality of frames and, if an amount of change of the frame power between a current frame and a past frame exceeds a pre-set threshold, said noise domain detection means deems said current frame to be a speech domain, even if said current domain is the noise domain.

14. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means detects the noise domain in view of the value of the analytic parameters over plural consecutive frames.

15. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein said noise domain detection means performs filtering on a noise level output of the noise domain detected by said noise domain detection means.

16. The speech signal transmitting and receiving apparatus as claimed in claim 1 wherein the filtering performed by said noise level detection means on the noise level output is minimum value filtering.

17. A speech signal transmitting and receiving apparatus having a transmitter and a receiver, comprising:

noise level detection means for detecting a sound signal level entering a transmitting microphone as a noise level when there is no transmitting speech input at said transmitter; and

control means for controlling a volume of sound reproduced from a compressed speech signal received from another transmitter responsive to the noise level detected by said noise level detection means.

18. The speech signal transmitting and receiving apparatus as claimed in claim 17 wherein said noise level detection means detects the sound level entering said transmitting microphone of the transmitter directly after turning on of a power source for talk transmission.

19. The speech signal transmitting and receiving apparatus as claimed in claim 18 wherein said noise level detection means detects the sound level entering said transmitting microphone when the sound level in said receiver exceeds a pre-set value.

20. The speech signal transmitting and receiving apparatus as claimed in claim 17 wherein said noise level detection means detects the sound level entering said transmitting microphone at a pre-set time interval in the standby state of said transmitter for signal reception.

21. The speech signal transmitting and receiving apparatus as claimed in claim 20 wherein said noise level detection means detects the sound level entering said transmitting microphone when the sound level in said receiver exceeds a pre-set value.

22. The speech signal transmitting and receiving apparatus as claimed in claim 17 wherein said noise level detection means detects the sound level entering said transmitting microphone when the sound level in said receiver exceeds a pre-set value.