I have been utterly confused as to what exactly happens in a sound wave and how it is produced.I understand the mathematical description of it quite well, what I don't get is its qualitative description.
So suppose I have a long air tube and I create a sound wave travelling right by sinusoidally moving the piston right and left. Now here are my questions:
- Doesn't pushing the piston change the volume of the tube and as a result the pressure through out the tube changes? Then how come the pressure vary sinusoidally?
- I read a bunch of books but no one book seems to explicitly explain how the sound wave is produced. I have read that pushing the piston compresses the layers of air next it causing the pressure and density to increase there. Then does this region of increased pressure cause the adjacent layers to compress or is the air molecules in this high pressure region push the layers adjacent to them causing them to compress?
- If the above description is correct then how come the displacement and pressure equations are out of phase by π/2? I.e how come when the pressure variation at a place is zero then the displacement of air molecules is maximum there?
- Can someone provide a qualitative description of how a sound wave is produced by sinusoidally moving the piston in the air tube?