noun
dilation (acoustics)
Technical term in acoustics for the expansion phase of a sound wave, opposite of compression (圧縮度).
音波の膨張度と圧縮度を測定する。
Measure the dilation and compression of the sound wave.
Compound of 膨張 (expansion) + 度 (degree). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.