deaden

verb (used with object)

1. to make less sensitive, active, energetic, or forcible; weaken: to deaden sound; to deaden the senses; to deaden the force of a blow.
2. to lessen the velocity of; retard: to deaden the headway of a ship.
3. to make impervious to sound, as a floor.

verb (used without object)

4. to become dead.

verb

1. to make or become less sensitive, intense, lively, etc; damp or be damped down; dull
2. (tr) to make acoustically less resonanthe deadened the room with heavy curtains

v.

1660s “deprive of or diminish (some quality),” from dead (adj.) + -en (1). Earlier the verb was simply dead. Related: Deadened; deadening.