donkey kong - something wrong with my sound?

[big daddy]

DK on mame, the monkey climbs to the top, then stomps and the gratings fall.  I always remembered a big "boom, boom, boom, boom" with each stomp then "duh-duh, duh-duh, duh-duh".

I don't get those booms though.  Also when mario jumps I remember a "boing" but I don't get any sound on the jumps.

I have both speakers set up and have verified they work, but wondering why I'm not hearing those 2 sounds.  I don't notice any other abnormalities on any other games. 

[2600]

Do you have the samples?

[whammoed]

Yep, you need samples:
http://www.mame.net/downsamples.html