Undercover Cops sound problem?

Hi, I installed Lakka on Raspberry Pi 3 and I’d like to play Undercover Cops (arcade version).

On FBA core it’s OK but it’s a bit slow (I get 56 fps) while on MAME 2003 it’s in full speed (60fps) but sound is somehow corrupted. Game ROM should be OK (from the MAME 2003 Reference Romset, Un-merged) so I’d like to ask: maybe someone could confirm that it’s not an issue related to my romset?

Thank you very much!