Question

How is the speed of sound in air affected by pressure of air?

• A. no effect
• B. decreases with the increase in pressure
• C. increases with the increase in pressure
• D. data insufficient

Answer 1

The correct option is A no effect

Air pressure has almost no effect on sound speed. It has no effect at all in an ideal gas approximation, because pressure and density both contribute to sound velocity equally, and in an ideal gas the two effects cancel out.
In an ideal gas, intermolecular gaps are always taken to be very large, regardless of pressure. Pressure is solely due to the interaction with (imaginary) walls, not due to the interaction between molecules.