1. Doppler Effect

2. Resting sound source Frequency fs V=340m/s Frequency fo source at rest
observer
at rest

3. Sound source moving toward observer
Observer hears
increased pitch
(shorter wave length)
Frequency fo
Frequency fs
source
observer
at rest

4. Sound source moving away from observer
Observer hears
decreased pitch
(longer wave length)
Frequency fo
Frequency fs
observer
at rest
source

5. Frequency heard by observer
Source moving toward observer.
Perceived wavelength:
With
Observer:

6. Observed frequency Source toward observer: Source away from observer:
Increased frequency
Source away from observer:
Decreased frequency