‘扩音’ literally combines 扩 (kuò), meaning 'to expand' or 'to amplify', and 音 (yīn), meaning 'sound' or 'tone'. Together, they form a noun meaning 'sound amplification' — the technical process or equipment used to increase sound volume, such as microphones, speakers, or public address systems. It is commonly used in contexts involving audio engineering, live events, classrooms, or medical devices like hearing aids.

The term is neutral in register and appears frequently in both written and spoken Chinese, especially when discussing audio technology, accessibility tools, or communication support. While it can refer to the abstract concept of amplification, it often functions as a modifier (e.g., 扩音设备 'amplification equipment') or appears in compound nouns rather than standing alone as a verb. It is not related to biological or natural sound production — it always implies artificial enhancement of acoustic output.