2. Beats = Some Graphs

3. Recall what a single frequency tone sounds like Play on Sound Generator A=440 Hz. The Graph:

4. 440 Hz. and 450 Hz. Compared 440 Hz. 450 Hz.

5. 440 Hz. and 450 Hz. Together

6. 440 Hz. and 450 Hz. Together for a longer time (0.1 second)

7. 440 Hz. and 450 Hz. Together for an even longer time (0.5 second) T beat From this graph we see that T beat = 0.1 seconds. f beat = 10 Hz..

8. Why?? In phase out of phase in phase again

9. The Concept Two sounds start together (in phase). After T beat seconds they get back together again. One of the waves must have gone through N cycles while the other went through (N+1) complete cycles. They are therefore together again!

10. The *(*@)$# math The beat frequency between two simultaneous tones is equal to The difference between the frequencies of the two tones!

11. LISTEN & Look……. Isn’t science wonderful??