Interference and Sound Waves

Recipe of Music

Beats

Important: You can not say what frequency is higher!!!!

Doppler Effect

Shock Waves and Sonic Boom

1. What is the different ways to increase the fundamental frequency of a note played on a guitar string?

2. An automobile sounding its horn is moving toward you at a constant speed. How does the frequency you hear compare with that heard by the driver?

3. Why don’t we hear beat when adjacent keys on a pianop are hit at the same time?

1. You can tune the frequency of a guitar string without changing its length. To tune a flute, however, you have to slightly adjust the length of the tube. How do you account for this difference?

2. Electronic signal generators can produce pure sound frequencies with great precision. Why then is it so difficult to make an electronic piano that sounds like an acoustic piano?

1. Why is the low E-string on a guitar made of thicker wire that the high-E string?

2. Billy and Elaine are holding electric buzzers that sound at slightly different frequencies. When they are both standing still, the two buzzers produce the beat frequency of 4 hertz. Elaine begins to run away, and Billy hears the beat frequency gradually increase. Whose buzzer has the higher frequency? Explain.

Baby-Quiz 1. On what two places on a guitar string of length L could you

place you finger to damp out the second harmonic? Would the fourth harmonic be damped out if you placed your finger at either of these locations?

2. What happens to the fundamental frequency of an organ pipe as the temperature in the room decreases? Explain.

3. The two wires corresponding to one key on a piano are out of tune. If we decrease the tension of the wire producing the lower frequency, will the beat frequency increase, decrease, or stay the same?

4. Describe the sounds you would hear if a train passed you with its whistle blowing.