Methods and apparatus for echo cancellation in a system having a speaker
and a microphone are disclosed. The speaker receives a speaker signal
x(t). The microphone receives a microphone signal d(t) containing a local
signal s(t) and an echo signal x.sub.1(t) that is dependent on the
speaker signal x(t). The microphone signal d(t) is filtered in parallel
with first and second adaptive filters having complementary echo
cancellation properties relative to each other. A minimum echo output
e.sub.3(t) is determined from an output e.sub.1(t) of the first adaptive
filter and an output e.sub.2(t) of the second adaptive filter. The
minimum echo output has a smaller energy and less correlation to the
speaker signal x(t). A microphone output is then generated using the
minimum echo output e.sub.3(t).