萨克斯管的吹嘴需要定期清洁以保持良好的音质。

The ___mouthpiece of the saxophone needs regular cleaning to maintain good sound quality.

这家杂志成了该公司的传声筒，只发布对他们有利的新闻。

The magazine served as a ___mouthpiece for the company, only publishing news that favored them.

拳击手在训练前总是记得戴上护齿套。

The boxer always remembers to wear his ___mouthpiece before training.