Video answer: The sine wave explained (ac waveform analysis)
Top best answers to the question «Why is sound a sine wave»
As described above, the air pressure rises and falls. For a single-frequency sound wave, the rate at which it does this is regular and continuous, taking the shape of a sine wave. Thus, the graph of a sound wave is a simple sine wave only if the sound has only one frequency component in it – that is, just one pitch.
Video answer: Can you hear the difference between a sine wave and a square wave?