Top 士 is the scholar radical and the entry's filing point. It replaces the much fuller traditional 聲 top (殸, a chime-stone struck by a hand); the simplification kept just this 士-shape silhouette and parked the character under the gentleman radical.
ideograph
声shēng
sound (lower fused body)
Cliff-like lower body functions as a fused residual silhouette with no standalone CJK reading - treat as the leftover ear-listening shape that survived simplification. Historically the heavily reduced remainder of traditional 聲's bottom 耳 (ear) element after the 1956 reform collapsed the full form.