Air as a vibrating object with resonance?

Question

Hi, I have a homework question from my acoustics class that I'm a little confused about:

Can air be a vibrating object with a natural resonant frequency? Explain.

This is the answer that I came up with: No, this is because a resonator requires a hollow body or cavity which allows for its vibration. Air in this case can only act as a medium transferring vibrations to the other vibrating system.

I'm not completely confident with my answer. Can anyone let me know if I'm on the right track? Thank you so much, I really appreciate the help!

Answer 1

Resonance comes from something having a natural frequency at which vibrations have less damping. Almost any solid object has a resonant frequency. Bridges are one that all military people are taught about. They are told not to march in step at a consistent cadence. For a volume of air to have a resonant frequency it needs to have a definitive boundary that will reflect the wave from one part of the volume to another and back. I have experienced hearing whispers at a distance using parabolic shaped barriers. I assume that if you used a source of waves that had an appropriate wave length and a pair of such parabolic shaped devices one could set up a resonance without a connecting tube.

Answer 2

a harmonica use air that resounds