Speex dev - Jun 2010 - Sound card problem in acoustic echo cancellation

Hi All,

I am a research associate in the Hong Kong Polytechnic University. One of
my research interests is acoustic echo cancellation. Now I meet a big problem.
When I was testing my own AEC module, I found that it was almost perfect in
few computers but much worse in other computers. Then I tried AEC module in
speex, it was almost the same result.

Then I found the reason is that sound cards of most computers have different
sampling and playing rate, so it is almost impossible for the adaptive filter
to converge and reach best result. For example, long time average sampling and
playing rate of a sound card is 7999.864Hz and 7980.129Hz respectively. Sound
cards of the computers which shown perfect AEC result are the only sound cards
which keep the same sampling and playing rate.

Then, what can I do to solve the problem? Could you please give me any advice?
BTW: I am working on Windows XP platform and I have tried DirectSound.

Your Sincerely
Li Maoquan