Sound+Questions

1. The vibration of an object causes variations in ?? which are transmitted through the air in sound waves.
 * Air molecules**

2. As the sound wave travels through the air the air molecules experience (being pushed together),and (pulling apart). Pushed together is called:?? **compression** Molecules pulled apart is called:?? **refraction**

3. The frequency range of human hearing is from ? Hz to ? kHz  **20 Hz to 20 kHz**

4. The perceived intensity or volume of a sound is measured in units called ??  **amplitude**

5. The intensity level known as the “threshold of pain” is ??  **120 dB**

6. List four waveforms commonly used as building blocks for synthesis: **a. sine - only has fundamental pitch** **b. square - has every other harmonic (all the odds)** **c. sawtooth - has all harmonics** **d. triangle - tapers off quickly** **has to do with how many harmonics are present** **complex waves - natural sounds, like voices**

7. The frequency of a pitch one octave higher than 450 Hz is _Hz.
 * 900 Hz**

8. To double the loudness of a sound, the power must increase ?? times.
 * 10 times**

9. The amount of energy expended in making a sound is called the power of the sound and is measured in ??
 * Watts**

10. The predominant perceived pitch of a timbre is called the ?? **fundamental.**

11. The series of frequencies present in a timbre is called the ?? series. **Harmonic/overtone series**

12. “Cycles per second” or “cps” measures what aspect of sound?

13. Amplitude is a measurement of a sound's ??
 * Loudness**

14. Timbre or tone color is created by the many different ?? present in a sound.
 * Harmonics**

15. Describe the Doppler Effect. **(Car going by)**

**Comb filtering:** waves out of phase with each other creates little peaks and valleys; use absorption and diffusion to get rid of it. Diffusion on back wall, absorption in corners for bass traps

**standing waves:** the waves that will cancel or boost measure by finding l, w, and h of the room; use half speed of sound - find each frequency and find all the harmonics, compare. Modes with similar frequency zones would be likely to cancel or boost.

In order for a sound to be perceived as twice as loud, it has to be actually 10 times louder.

double distance from sound, drops 6 dB.

clap echo - between 2 parallel surfaces