also: おとあな
noun
tone hole
Technical term in music; an opening on a wind instrument that is covered or uncovered to change pitch.
See also: トーンホール
フルートの音孔を指でふさぐと音程が変わる。
Covering the tone holes on a flute with your fingers changes the pitch.
この楽器には音孔が六つある。
This instrument has six tone holes.
Synonymous loanword from English; トーンホール is more common in modern musical instrument contexts, while 音孔 is a native Japanese term.
Compound of 音 (sound) and 孔 (hole). The reading おんこう follows the on'yomi pattern, while おとあな is a mixed reading.