acoustic modem acoustic modem /əˈkuːstɪk ˈmoʊdəm/

noun

1. A modem that converts electrical signals to telephone tones and back again  ( acoustic modem )
   a modem that converts electrical signals to telephone tones and back again
    In the early days of internet connectivity, many people used an acoustic modem.
   In the early days of internet connectivity, many people used an acoustic modem.