Que informação mais… inútil:
True Story: 7Hz is the resonant frequency of a chicken’s skull cavity. This was determined empirically in Australia, where a new factory generating 7Hz tones was located too close to a chicken ranch: When the factory started up, all the chickens died. — Turbo C++ 3.0 for DOS Help File
此为borland c++帮助文档中，关于sound函数中的一段话。不过我对此仍有怀疑