echo after playing the sound
 

Hello

When I play a sound I can hear the short unexpected sound at the end.
This unexpected sound lasts no more than a second and gives the effect of echo.
It looks like a part of the original file is repeated at the end.
This unexpected sound is not contained in a file.
I observe it when playing mp3 file using both mplayer and mpg123.
It happens on both my sound cards working in distinct machines:

Sound Blaster Live! (driver: EMU10K1)
Intel Corporation HD Audio Controller (driver: HDA Intel)

I realized recently that this problem occured about a year ago when I updated my system with:
emerge --update world

Please give me any indications of how to solve this problem.
Below are some details about my configuration:

kernel 2.6.24.3 (OSS not included)
mplayer-1.0_rc2_p25993
mpg123-1.2.0

Great
Thanks for help