Sound Pressure in Partial Vacuum

[Yoni V]

Is there a good description or formula regarding how the sound pressure from a constant source depends upon ambient pressure?
That is, if I were to conduct an experiment where I put a source and a microphone in a container, and then change the pressure in that container with a pump, assuming that the temperature remains relatively constant, how will the microphone react to the change in pressure? Thanks

 

[Bystander]

https://en.wikipedia.org/wiki/Speed_of_sound