unacoustic

adjective4

1. •
   Having poor acoustic properties; not conducive to the projection of sound; tending to muffle or muddy sounds.

   • This unacoustic vastness swallows the earth sounds and produces the effect of silence upon the soul. — 1914
2. •
   Not acoustic; electronically generated or amplified.

   • Our next respondent agrees with the previous opinion but also points out interest in using the computer for synthesizing original 'unacoustic' sounds. — 1997
3. •
   Lacking sound or sonority; silent or muffled.

   • The deaf-mutes from a separate community among the hearing people. The most interesting question in their psychology is: What is their conception of the outer world? Of an unacoustic, mute world? — 1940
4. •
   Having a frequency outside the range of audible sounds.