Sound1. Energy is transferred from

particle to particle through matter.

2. How we hear a. Outer ear collects sound. b. Middle ear amplifies

sound. c. Inner ear converts sound.

3. Properties of sound a. Intensity and loudness 1) Intensity depends on

the energy in a sound wave. 2) Loudness is human

perception of intensity. 3) Loudness is measured

on the decibel scale.

a) Threshold of hearing (0 db) b) Threshold of pain (120 db)

b. Frequency and pitch 1) High frequency means more vibrations hitting the ear. 2) Pitch is how high or how low a sound seems to be. 3) Healthy humans can hear from 20 Hz to 20,000 Hz 4) We are most sensitive from 440 Hz to 7,000 Hz.

5) Ultrasonic sound has a frequency greater than 20,000 Hz. a) Dogs (up to 35,000 Hz) b) Bats (over 100,000 Hz) c) Medical diagnosis

6) Infrasonic sound has a frequency below 20 Hz; they are felt rather than heard(earthquakes, heavy machinery).

Speed of SoundMedium velocity m/sec

air (20 C) 343air (0 C) 331water (25 C) 1493sea water 1533diamond 12000iron 5130copper 3560

glass 5640Which medium does sound travel fastest?

Slowest?

c. Speed of sound 1) 332 m/s in air at 0 C. 2) Changes by 0.6 m/s for every Celsius degree from 0 C. 3) Subsonic – slower 4) Supersonic – faster than sound (Mach 1 = speed of sound) 5) Sonic boom (pressure cone)

SONIC BOOM

d. The Doppler effect – the change in pitch due to a moving wave source. 1) Objects moving toward you cause a higher pitched sound. 2) Objects moving away cause sound of lower pitch. 3) Used in radar by police and meteorologists and in astronomy.

Doppler Effectis the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound.

Doppler Effect

4. Musical sound a. Noise has no pattern. b. Music has a pattern and

deliberate pitches. (A)Noise

(B) Pure tones

(C) Musical notes

c. Sound quality describes differences of sounds that have the same pitch and loudness.

d. Every instrument has its own set of overtones.

e) Beats are pulsing variations of loudness caused by interference of sounds of slightly different frequencies.

5. Uses of sound waves a. Acoustics – the study of

sound.Soft materials dampen sound; hard materials reflect it (echoes

and reverberations). b. SONAR – Sound Navigation and Ranging (echolocation).

Sonar Active Passive

Passive

Sonar Video

TsunamiWave length, 500 to 600 km in ocean

Properties of Wave Video

Tsunami Wave

Tsunami WarningOn December 26, they were playing in the sea

when Tilly suddenly found the water was bubbling, like on top of a beer. She immediately realized tsunami was coming because the scene reminded her of a geography lesson about Hawaii's 1946 tsunami.

Right away, Tilly told her parents, sister and other tourists to escape quickly, but at first they were in half belief. However, seeing Tilly's serious and firm expression, people started to be convinced of the seriousness of the thing and instantly left the beach.

At last over 100 tourists were ended up in safety with no death