Method and apparatus of controlling noise level calculations in a conferencing system

1. For use in a conferencing system incorporating noise characteristic estimation of a first of two bidirectionally transmitted signals, the improvement comprising detecting at least one of voice activity and in-band tone activity in a signal transmitted in a first direction opposite to said first signal and in response ceasing said noise characteristic estimation and

further comprising detecting at least one of voice activity and in-band tone activity in said first signal and in response ceasing said noise characteristic estimation in a direction of said first signal.

2. The improvement of claim 1 , wherein said noise characteristic is noise level.

3. The improvement of claim 1 , wherein said noise characteristic is noise level.

4. Apparatus for controlling noise characteristic estimation in a conferencing system, comprising:

a first noise characteristic estimator for estimating a noise characteristic of a signal of interest transmitted in a first direction through said conferencing system;

a first voice activity detector for detecting at least one of voice activity and in-band tone activity in a signal transmitted through said conferencing system in a direction opposite to said signal of interest and in response disabling the first noise characteristic estimator,

a second noise characteristic estimator for estimating a noise characteristic of a signal of interest transmitted in a direction opposite to said first direction, through said conferencing system; and

a second voice activity detector for detecting at least one of voice activity and in-band tone activity in a signal transmitted through said conferencing system in said first direction and in response disabling the second noise characteristic estimator.

5. The apparatus of claim 4 , wherein said noise characteristic is noise level.

6. A conferencing system, comprising:

a line input for receiving a line-in audio signal from an audio signal line;

a line output for transmitting a line-out audio signal to said audio line;

a speaker connected to said line input for broadcasting said line-in audio signal;

a microphone connected to said line output for applying said line-out audio signal to said line output;

an echo canceller connected to said line input and said line output for canceling echo signals of said line-in audio signal appearing in said line-out audio signal;

at least two noise level estimators, one of said noise level estimators for estimating noise level in said line-in audio signal and the other of said noise level estimators for estimating noise level in said line-out audio signal; and

at least two voice activity detectors, one of said voice activity detectors for detecting voice activity in said line-in audio signal and in response disabling said other of said noise level estimators, and the other of said voice activity detectors for detecting voice activity in said line-out audio signal and in response disabling said one of said noise level estimators.

7. The conferencing system of claim 6 , wherein said other of said voice activity detectors is connected to said line-output and said echo canceller, and said one of said voice activity detectors is connected to said line input.

8. The conferencing system of claim 6 , wherein said other of said voice activity detectors is connected to said microphone and said echo canceller.