Patent ID: 7366294

Claim:
In a communication system adapted to transmit a communication signal comprising an input speech component and an input tonal component, apparatus for maintaining the input tonal component comprising: an input for receiving the communication signal; a processor arranged to: detect the input tonal component; substantially suppress an output of a noise suppressor configured to suppress noise in the communication signal, including the input speech component and input tonal component, based on a detection of the input tonal component; generate a second tonal component in response to the input tonal component, wherein the second tonal component has a frequency matched to the input tonal component frequency; validate detection of the input tonal component; and generate an output signal based on at least a partial validation, the output signal comprising at least part of the second tonal component and at least part of a signal representative of a characteristic of the input tonal component with the output signal time duration being greater than the input tonal component time duration or generate, based on a non-validation, an output signal comprising the output of the noise suppressor in an unsuppressed state; and an output for transmitting the output signal, including the second tonal component.