Intercom Question

I have an intercom that allows me to listen/talk to anybody in front of my
door. There is a switch that allows the speaker to act as a microphone. The
speaker also emits a very anoying piercing sound whenever the doorbell
button is pressed. Is there a component i can place in series or parallel to
the speaker/mic to limit the sound without affecting the intercom
capabilities?
Unfortunately the the electronics to this unit is located in another part of
my complex.. Any assistance appreciated.

 

Is that a wireless doorbell?

 

Not wireless

 

Odd that it's not a 60Hz buzz you hear...what frequency would you estimate?
Is the door bell part of the intercom as in those often removed 70's units
by Nutone?
Those unit make the AM/FM radio part of the intercom too.