microphonous

adjective2

1. •
   (old-fashioned, rare) Heard through a microphone.

   • The invasion of the microphonous tribe began in February, when Dusty and Goldie […] — 1926
2. •
   (no longer used, rare) Serving to augment the intensity of weak sounds; amplifying.

   • Innumerable degrees of crime, but a whisper in the era of Kent and Blackstone, are now of microphonous volume in strenuousness, and as common as the asphyxial conditions which create it. — 1904