An ambulance drives by with a blaring siren.

the change in pitch you hear as it passes is called the

sonar effect
infrasound effect
intensity effect
doppler effect

Answer;

Doppler effect

Explanation;The pitch of the siren of a Fire truck appears to change as the truck passes us due to the Doppler effect.Doppler effect is the tendency to increase or decrease the wavelength of the sound due to the motion of the source. Therefore; when the ambulance is approaching ab observer, the wavelength is decreased and the pitch of the sound also increases as compared to when the ambulance is at rest.When the ambulance passes and is moving away from an observer, the wavelength is increased and the pitch is decreased below the value when the source is at rest.