The hands-free telephone problem
Eberhard Hänsler · 2003
The author describes the problem of providing the means for a comfortable hand-free telephone conversation. After a report on conventional schemes the properties of a loudspeaker-enclosure-microphone system are discussed. It is shown that for a truly two-way conversation the decoupling of the loudspeaker and the microphone requires an adaptive filter with an impulse response of several hundreds of milliseconds in duration. The attempts to solve the adaptation problem are outlined.>