soundproof

/S AW1 N D P R UW0 F/
verb
  1. 1

    To make resistant to transmitting sound.

    โ€œWe soundproofed the room so we couldn't hear the road noises; unfortunately we couldn't hear the fire alarm either.โ€

adjective
  1. 1

    Not allowing sound through.

    โ€œThe contestant was placed in a soundproof booth so he could not receive help from the audience.โ€

Source: https://en.wiktionary.org/wiki/soundproof