Patent ID: 8571039

Claim:
A method of transmitting an audio signal over a communication channel, the method comprising: encoding the audio signal with an encoder using a first sampling rate; filtering the audio signal using a first cut off frequency, the first cut off frequency being chosen in dependence upon the first sampling rate, wherein the step of filtering is performed after the step of encoding; and transmitting the encoded and filtered audio signal over the communication channel, wherein the method further comprises: determining the presence of a condition in which the sampling rate of the encoder is to be switched to a second sampling rate at a switching time; and if the condition has been determined to be present, gradually changing the cut off frequency used in the filtering step from the first cut off frequency to a second cut off frequency, the second cut off frequency being chosen in dependence upon the second sampling rate, such that the audio bandwidth of the transmitted signal changes gradually when the sampling rate is switched to the second sampling rate.