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side tone

British  

noun

  1. sound diverted from a telephone microphone to the earpiece so that a speaker hears his own voice at the same level and position as that of the respondent

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

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By "side tone" is meant the noises which are produced in the receiver at a station by virtue of the action of the transmitter at that station.

From Cyclopedia of Telephony & Telegraphy Vol. 1 A General Reference Work on Telephony, etc. etc. by Miller, Kempster

This circuit is very efficient, but is subject to the objection of producing a heavy side tone in the receiver of the transmitting station.

From Cyclopedia of Telephony & Telegraphy Vol. 1 A General Reference Work on Telephony, etc. etc. by Miller, Kempster