As the frequency of a sound wave increases or decreases, what happens to its pitch

Both frequency and wavelength will change. We perceive an increase of frequency as the increased pitch that you described. As the frequency (pitch) increases, the wavelength becomes shorter according to the universal wave equation ( v=fλ ).

Explanation:

If the frequency of a sound wave increases, the wavelength of the wave decreases. You hear the pitch of the sound from an ambulance siren get lower, then get higher.

( happy to help) :)

this is poiselle's equation from fluid mechanic in physics. mech eng