'Kū shēng' literally combines 哭 (kū), meaning 'to cry', and 声 (shēng), meaning 'sound' or 'voice'. Together, it refers specifically to the audible sound produced when someone cries — not the act of crying itself, but the vocal expression: a wail, sob, or whimper. It emphasizes the acoustic quality rather than the emotional state.

This noun is commonly used in descriptive, narrative, or observational contexts — for example, in literature, news reports about distressing events, or everyday descriptions of babies or upset children. It often appears with verbs like 听到 (tīng dào, 'to hear'), 发出 (fā chū, 'to emit'), or 传来 (chuán lái, 'to come from afar'). Unlike the verb 哭, 哭声 is never used as a verb and cannot take aspect markers like 了 or 过.