Refers to the aerodynamic phenomenon where an aircraft approaches the speed of sound, often used in contexts like breaking the sound barrier.
その戦闘機は音の壁を突破した。
The fighter jet broke the sound barrier.
Compound of 音 (oto, 'sound') + の (no, possessive particle) + 壁 (kabe, 'wall'), literally 'wall of sound'. A calque of English 'sound barrier'.