/ˈmaʊθpiːs/
mouth·piece
BrE /ˈmaʊθpiːs/
NAmE /ˈmaʊθpiːs/
the part of the telephone that is next to your mouth when you speak
the part of a musical instrument that you place between your lips
~ (of/for sb)
a person, newspaper, etc. that speaks on behalf of another person or group of people
The newspaper has become the official mouthpiece of the opposition party.
The Press Secretary serves as the President’s mouthpiece.