pulseaudio module to mute other sources?

[Joe Pfeiffer <pfeiffer@cs.nmsu.edu>]

I'm reasonably confident there must be a better place to post this than
this newsgroup, so answers telling me where to look will be just as
welcome as any that address the question!  I'm a Debian user, so this is
where I'm trying first....

Is there a pulseaudio module that will detect when an audio source isn't
silent, and mute other sources in that cases?

It may be more clear if I describe my particular desire use case.  I
have a ham radio, whose audio output I can plug into my sound card
input.  I'd like to be listening to music, but when a call comes in on
the radio have it mute any other audio.

Any thoughts?