音
オン, イン, ノン, おと, ね, お, と

sound, noise

JLPT4 G1 S9 F491

The relevant seal inscription form shows 言# words + a line in the mouth element at the bottom → *indistinct utterance* contained in (not emanating as speech from) the mouth (compare 吟) → *sound*; *noise*; *tone* → *news/word of*; *ON reading* of a Han/Chinese character (← read a character by its Sino-Japanese sound; the contrast is to 訓, where the idea is to grasp the signification of a character).

[Full Kanji Etymology List]