mouthpiece

The aperture of a wind instrument into which the player blows directly.

A spokesperson (as a lawyer).

(especially boxing) equipment that protects an athlete's mouth.

An acoustic device; the part of a telephone into which a person speaks.

A part that goes over or into the mouth of a person.

“the mouthpiece of a respirator”

The tube of a pipe or cigarette holder that a smoker holds in the mouth.