聲 (traditional) was originally a picture of striking a 磬 (a stone chime) plus 耳 (ear) — the upper 殸 is a hand with a mallet striking a stone instrument, the lower 耳 is the ear hearing it. From an instrument's sound reaching the ear came "sound, voice." The shinjitai and simplified kept only the upper part, greatly reducing it to 声.

So the form splits: traditional (ko/en/es) is 聲, shinjitai (ja) and simplified (zh) are 声 — a sharp difference in stroke count (聲 17 vs 声 7).

Korean hanja-sound "seong": 音聲 (eumseong, voice / audio), 聲帶 (seongdae, vocal cords), 名聲 (myeongseong, fame), 歡聲 (hwanseong, cheers), 聲明 (seongmyeong, a statement). Korea uses the traditional 聲.

Mandarin: shēng, 1st tone. 声音 (shēngyīn, sound), 大声 (dàshēng, loud), 声调 (shēngdiào, tone), 相声 (xiàngsheng, crosstalk comedy), 名声 (míngshēng, reputation). It is the 声 of the four tones of Mandarin — 第一声 (the first tone).

Japanese: on-readings セイ (sei) and ショウ (shō), kun こえ (koe) and こわ (kowa). 声 (koe, voice), 音声 (onsei, voice / audio), 声優 (seiyū, voice actor), 歓声 (kansei, cheers), 名声 (meisei, fame). Before a compound こえ shifts to こわ — 声色 (kowairo, tone of voice).

Memory aid: striking a stone chime heard by the ear — the traditional has the ear (耳), the shinjitai keeps only the top.