資料來源 : Free On-Line Dictionary of Computing

acoustic coupler
     
         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 {British
        Telecom} 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)