Not sure. Try the following:
1) soft-reset your device (the recessed button on the back, press it with the stylus tip)
2) make sure your volume is not set to minimum/off
3) disable sounds for screen taps/buttons etc.
4) make sure you select the checkbox beside "Sound" in MAMECE-10X before starting the game.

Darren

> HI Darren, I ve play with games with sound in your list
like centipede,galaxian
> or 1942 but the sound doesnt work...I have a cassiopeia e.105 ,what the
> problem?? many thaks!!!
>