Wiktionary
n. 1 An interface device for coupling electrical signals by acoustical means — usually into and out of a telephone instrument. 2 A terminal device used to link data terminals and radio sets with the telephone network.
Wikipedia
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone instrument.
The link is achieved through converting electric signals from the phone line to sound and reconvert sound to electric signals needed for the end terminal, such as a teletypewriter, and back, rather than through direct electrical connection.
Usage examples of "acoustic coupler".
Essentially, it's a keyboard and acoustic coupler built into one device.
For bigger problems with which the little computer couldn't cope there was a modem and an acoustic coupler so that the little chap could be used as a terminal to control a big computer by way of 'the post office land lines.
For bigger problems with which the little computer couldn't cope there was a modem and an acoustic coupler so that the little chap could be used as a terminal to control a big computer by way of the post office land lines.