mouthpiece
n
1 part of a musical instrument, pipe, telephone, etc that is placed at or between the lips （乐器的）吹口; （烟斗的）咬嘴; （电话的）送话口. =>illus at App 1 见附录1插图, page x.
2 (usu derog 通常作贬义) person, newspaper, etc that expresses the opinions of others 代言人; 喉舌
a newspaper which is merely the mouthpiece of the Tory party 仅为英国保守党喉舌的报纸.