Theory Thursday No. 6

What is a Sound Wave?

The simple answer: Sound is a longitudinal wave of disturbance in the air.

The vibrations of sound are measured in cycles per second. The unit to measure sound is called Hertz (Hz). This has no relation to Hertz car rental by the way... ;)
The human ear can register 20 to 20,000 Hz. This changes as we age. The violin's range is about 220 Hz to around 3,500 Hz. In orchestra, we tune to A 440 Hz. The image below shows a sine wave of A 440 Hz and then the A an octave above it.

Below are some interesting videos you should check out. More proof for how much of an impact sound, music, and this form of energy have on our daily lives. Music can move you! Literally.

Interesting facts:
**Ferrets have one of the lowest Hz wave frequency ranges of hearing (as low as 10 Hz). They have a strong ability to sense and map the direction of where a sound came from. Bottlenose dolphins have some of the highest frequency ranges of hearing (going above 150,000 Hzs. That is 7 times more sensitive than the human ear). These animals can hear things humans are incapable of. That is pretty cool!

**The term Hertz was named after Heinrich Hertz, a German physicist who proved the existence of electromagnetic waves.

Below is a link that illustrates different instrument ranges. Can you find the violin?
http://www.guitarbuilding.org/wp-content/uploads/2014/06/Instrument-Sound-EQ-Chart.pdf

What to learn even more about the physics of sound?
http://acousticslab.org/psychoacoustics/PMFiles/Module02.htm

Have fun exploring the science of sound waves!
Larissa