# Sound Produced due to motion of air inside a tube

I'm trying to understand the sound produced by Air motion inside the respiratory system. If you have a long tube with a suction apparatus at one end , You turn on the apparatus and the air is sucked in. Now Sound waves are produced due to vibration of the molecules in the wall so that each molecule behaves like a harmonic oscillator and the whole is a system of coupled oscillators . I have some questions. If The air inside the tube is highly collaminated in its motion , That is it has zero component of velocity perpendicular to the axis , The there will not be any sound waves that are produced . If there is a very small inhomogeinity at the beginning then inside the tube will these inhomogenities be amplified ?

How does The Frequency and intensity depends on the velocity of air , The diameter of the tube and the degree of disturbance in the motion of air ?(I expect that sound will be a linear combination of waves with different frequencies , the more the turbulence , the more terms will be in the series expansion , The less diameter the more velocity and subsequently the bigger values of frequencies that appear in the series)

Will sound waves emitted have the same frequency along the tube, that is the velocity of and kinetic energy of air increases as they move along the axis and subsequently the energy of sound will increase or may be the higher velocity the more turbulence that occurs and subsequently sound waves will be a linear combinations of many waves with different frequencies ?

Why is the sound produced from a cavity amplified and has low frequency?(I expect this is due to turbulence , but in this case why does turbulence amplify sound?, I think that the more turbulence , the more frequencies produced and when you add them together , the amplitudes will tend to vanish for some frequencies and increase for other frequencies , right? )

Lastly , What exactly is the pitch of the sound and how is it related to the frequency?

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