what is your sound card ?
You can try this trick :
double click on the "Tennis.ini" file in your Tennis Elbow directory (usually, under "C:\Program Files\Tennis Elbow 2004\").
Change this line :
PanChange = -1
PanChange = 0
It'll disable the stereo effect, and maybe it'll solve your trouble.
Thanks to leave a message to tell the result...
== Mana Games ==
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