colo phones

Fri Apr 5 13:23:20 PST 2002

5 Apr 2002

Chuck Yerkes writes
> And the best way I've found to reduce noise when listening
> is to cover the MOUTHPIECE (or mute) - it's a full duplex
> setup, so you remove the machine room from being part of
> the conversation.

It's not the full duplex operation that makes covering the mouthpiece useful
in noisy environments.  It's the deliberate microphone-to-earphone feedback
(the "sidetone") that telephones employ to regulate talker volume.

Years ago Western Electric manufactured a handset intended for use in noisy
environments.  It resembled a conventional handset except that it had a
push-to-talk switch that energized its microphone, which was otherwise
muted.

Payne Freret