Usage patterns
〈漢字〉の音を調べるto look up the on-reading of a kanji
I looked up the on-reading of this kanji in the dictionary.
〈言語〉の音の数the number of distinct sounds (phonemes) in a language
Japanese has fewer distinct sounds than English.
〈漢字〉を音で読むto read a kanji using its on'yomi
When you read the kanji for "mountain" using its on'yomi, it becomes "san".
音と訓を区別するto distinguish the on-reading from the kun-reading
When studying kanji, it's important to distinguish on-readings from kun-readings.
Expressions
音頭を取るtake the lead; lead a group; lead a toast or cheer · sing the lead part of a song; lead a chorus