Is it possible to control the volume on the mame Simulator?

Way back then on Mame32 0.106:

• Options menu
• Default Game Options
• Sound tab
• Volume Attenuation slider, pull towards the left to reduce volume.

This would apply to all games.

Within games, volume down/up should be keys "-" and "=" by default, but it's not working for me. I'll update if I find out why.