What best describes the pitch that juan hears? the pitch remains constant as the ambulance moves toward and then away from juan. the pitch increases and decreases in a repeated pattern as the ambulance passes juan. the pitch drops to a lower pitch once the ambulance passes by juan. the pitch increases to a higher pitch once the ambulance passes by juan.

When there is relative motion between the source and the listener, the Doppler effect causes the frequency to rise or decrease. The frequency determines the pitch. When the frequency rises, the pitch rises with it.

When the source and the listener get closer to each other, the frequency rises. There is a reduction in frequency as the source and listener move away from each other.

Juan is standing on the street in the provided situation. When an ambulance approaches Juan and then passes by, the pitch dips to a lower level.

Hence "The pitch decreases to a lower pitch once the ambulance passes by Juan," is the right answer.

To learn more about the doppler effect refer to the link;

https://brainly.com/question/1330077