1. How do we hear?

3. Doppler Effect

4. Doppler Effect Due to moving sound source
closer to source = greater frequency
farther from source = lesser frequency
as sound moves towards listener the sound can be a high pitched whine
as sound moves away from listener the sound can be a drumming sound

5. Uses of the Doppler Effect
Doppler radar
police use it to determine speed of car
the frequency of the reflected (echo) sound wave gives you the speed
weather forecasters can use it to determine how fast a storm front is moving
determine the speed of stars relative to Earth

6. Breaking the sound barrier!
Why can’t
I hear
anything?

7. BOOM!!!

9. ULTRASOUND!