I have indeed noticed this phenomenon, though not with m37b7. A long time ago it used to happen to me with mame .35 final (I remember because the pitch would occasionally change in Money Puzzle Exchanger for T1). These days I no longer hear any changes despite using the same version from time to time, so I'm led to believe that it has something to do with your computer. At the time I had pitch changes I was using a Pentium II 300 MHz, 32 megs of RAM, and a Sound Blaster 16.(posted 8850 days ago)Cheers, Brian McLean