If the pitch of the sound coming out from a speaker increases, which is true about the sound wave?

(A) wavelength increases

(B) wavelength decreases

(C) amplitude increases

(D) amplitude decreases

B. Wavelength decreases.

Pitch of a sound depends on the frequency of sound wave. Frequency is the number of completed waves in one second. As wavelength decreases, number of waves that can be completed in one second will increase, meaning that the frequency will increase. As frequency increases, pitch of the sound increases.