24.1 Properties of Sound Notes

pitch

the perception of high or low that you hear at different frequencies of sound

decibel (dB)

A unit of measure of the intensity or strength of a sound.

Frequency Spectrum

Spectrum that shows loudness on the vertical axis and frequency on the horizontal axis.

Equal loudness curve

A graph which compares how loud you hear sounds of different frequencies.

Acoustics

The science & technology of sound.

Fact #1 about Sound

Sound is slower than light.

Speed of sound

1,000 km/hr (660 mph)

Speed of light

300,000 km/s (186,000 mi/s)

Supersonic

Term used to describe speeds faster than speed of sound.

Subsonic

Term used to describe speeds slower than the speed of sound

Shock wave

A cone-shaped wave produced by an object moving at supersonic speed through a fluid.

Sonic boom

The explosive sound heard when a shock wave from an object traveling faster than the speed of sound reaches a person's ears.

Sound travels about ______ in ___________.

A) Sound travels about 5x faster in water.

B)Sound travels about 18x faster in steel.

Example of traveling oscillation

Sound is a traveling oscillation.

Stronger restoring forces __________ the speed of sound. Increase or decrease?

Stronger restoring forces INCREASES the speed of sound.

Doppler Effect

An increase or decrease in frequency caused by the motion of the source of an oscillation (ex. sound).

Examples when you hear the Doppler Effect

You hear the Doppler effect when you hear a police or fire siren coming toward you, then going away from you.