教授那洪亮而清晰的声音让整个礼堂的学生都能听清他的演讲。

The professor's orotund voice ensured every student in the lecture hall could hear his speech clearly.

orotund 这个词由拉丁词根 oro-（"嘴"）和 rotundus（"圆形的"）组成。字面意思是"圆润的发音"，引申为形容声音"洪亮、圆润、清晰"，特别指演讲或朗诵时声音饱满有力、富有共鸣的特点。