tuning fork
A two-pronged metal instrument that produces a fixed pitch when struck, used for tuning musical instruments or in scientific demonstrations.
A piano tuner uses a tuning fork to get the reference pitch.
In science class, we struck a tuning fork to investigate how sound travels.
Simplified spelling using kana for the second character; less common but still encountered.
Compound of 音 (on, 'sound') and 叉 (sa, 'fork'), describing the instrument's shape and function. The reading is on'yomi.