Method and apparatus for providing comfort noise in communication system with discontinuous transmission

In a communication system for use in connection with an audio signal comprising interspersed speech present periods and silent periods, wherein said system comprises a transmitter and receiver at opposing sides of a signal transmission interface, and wherein said transmitter is disposed to transmit said audio signal to said receiver during said speech present periods and to discontinue transmission thereof during said silent periods, apparatus for providing comfort noise comprising:

• a comfort noise generator at said receiver side of said interface for producing comfort noise of adjustable amplitude;
• a first subsystem responsive to said silent periods for notifying said receiver to activate said generator when said transmitter discontinues transmission of said voice signal;
• and
• a second subsystem for transmitting a succession of amplitude parameters through said interface to selectively adjust the amplitude of said comfort noise generator in corresponding relationship with a noise level at said transmitter.