Care to give us an exact description of your problem? Maybe someone
here can help already. What's wrong with your intercom/headset
installation?

I use Avcom headset and I have two one for my passenger. When I Descend at 1000
feet per minute I get a loud squelch noise in bothe headsets.
2. when my passenger uses his own headset "Lightspeed" I get a noise which
comes and goes. If I put my hand on the radio it stops.
3 sometimes when I fly alone I get a squelch noise. Have the co-pilots side
shut of on my PSE.
Explained all this to my avionics shop and they can not find anything that
would cause this.