The traditional 聲 packed a whole concert: a hanging chime-stone 磬, a hand striking it, an ear 耳 receiving. Simplified 声 keeps the chime's silhouette. Sound, from instrument to eardrum, in one character.
声 rings through the language: 声音 (sound/voice), 大声 (loud — 大声点! speak up!), 小声 (quietly). Crucially for learners, the four tones are 声调 — 第一声, 第二声… (first tone, second tone): you've been saying 声 since your first pinyin lesson. 悄无声息 is silence; 名声 is reputation — the sound your name makes when you're not in the room.
The chime-stone struck — SOUND traveling to the ear.
The four tones you drill are 四声 — 'the four sounds'. Every pinyin mistake is a 声 problem.