echo

please help me im out of ideas. My computer sounds like
im in a tunnel. With kind of an echo effect. but more
like its really far away.This just started happening a
few weeks ago. I did not change anything. I keep reading
of others having this problem and they are told to turn
off their microphone. Well, i dont have mic plugged in
but i checked anyway and it is muted. Its not only music
its any program I run even when i turn on my computer.
The last thing that i did before it started happening was
upgrade music match and kaza but i dont see how that
would have caused it. I cant take it anymore please help.
Im using a creative soundcard.