An audio interface is coupled to received a music signal and a microphone signal. The music signal and a volume control signal are combined in a multiplier to produce a volume adjusted music signal. In response to an input signal from a user, the volume control signal is gradually changed in predetermined...http://www.google.de/patents/US6466833?utm_source=gb-gplus-sharePatent US6466833 - Method and apparatus for efficient memory use in digital audio applications
