acoustic coupler

hardware, communications A device used to connect a modem

to a telephone line via an ordinary handset. The acoustic

coupler converts electrical signals from the modem to sound

via a loudspeaker, against which the mouthpiece of a telephone

handset is placed. The earpiece is placed against a

microphone which converts sound to electrical signals which

return to the modem. The handset is inserted into a

sound-proof box containing the louspeaker and microphone to

avoid interference from ambient noise.

Acousitic couplers are now rarely used since most modems have

a direct electrical connection to the telephone line. This

avoids the signal degradation caused by conversion to and from

audio. Direct connection is not always possible, and was

actually illegal in the United Kingdom before BritishTelecom was privatised. BT's predecessor, the General Post

Office, did not allow subscribers to connect their own

equipment to the telephone line.

(1994-11-08)