Adaptive noise reduction technique for multi-point communication system

A method of suppressing noise in a signal, the method comprising inputting an input signal;

• repeatedly locating a noise level associated with the input signal to update a current noise level;
• and
• generating an output signal by:
• attenuating the input signal based on a first attenuation function if the input signal is within a first energy range, wherein the first energy range is defined based on the current noise level;
• and
• attenuating the input signal based on a second attenuation function if the input signal is not within the first energy range, wherein the second attenuation function is different from the first attenuation function.

A method of suppressing noise in a transmitted audio signal, the method comprising the steps of:

• inputting an audio signal;
• repeatedly locating a noise level associated with the audio signal while performing the inputting step, to update a current noise level;
• attenuating the audio signal using a first constant attenuation value if the audio signal is below the current noise level;
• attenuating the audio signal based on an exponential attenuation function if the audio signal is within a first range defined relative to the current noise level;
• and
• attenuating the audio signal using a second constant attenuation value if the input signal is not within the first range.

A machine-readable program storage medium tangibly embodying a program of instructions, the instructions executable on a computer system to perform a method of suppressing noise in a signal, the method comprising:

• inputting an input signal;
• repeatedly locating a noise level based on the input signal during said inputting;
• selecting an attenuation function from a plurality of selectable attenuation functions based on the input signal and a current state of the noise level, wherein a first one of the selectable attenuation functions specifies a minimum level for an output signal if the input signal corresponds to a first range, and a second one of the selectable attenuation functions specifies a range of levels for the output signal greater than the minimum level if the input signal corresponds to a second range higher than the first range;
• and
• applying the selected attenuation function to the signal.

A computer system comprising:

• a processor;
• and
• a memory coupled to the processor, wherein the processor is configured by instructions stored in the memory to:
• input an input signal;
• repeatedly locate a noise level associated with the input signal to update a current noise level;
• and
• generate an output signal by:
• attenuating the input signal based on a first attenuation function if the input signal is within a first energy range, wherein the first energy range is defined based on the current noise level;
• and
• attenuating the input signal based on a second attenuation function if the input signal is not within the first energy range, wherein the second attenuation function is different from the first attenuation function.

An apparatus comprising:

• means for inputting an input audio signal;
• means for repeatedly locating a noise level based on the input audio signal, while inputting the input audio signal, to update a current noise level;
• means for attenuating the input audio signal using a first constant attenuation value if the input audio signal is below the current noise level;
• means for attenuating the input audio signal based on an exponential attenuation function if the input signal exceeds the current noise level and is below a computed level greater than the noise level;
• and
• means for attenuating the input audio signal using a second constant attenuation value if the input signal exceeds the predetermined level.