Uses of Sound

a)Acoustics-the study of sound

b)Sonar-Sound Navigation and Ranging (echolocation)

c)Ultrasonic imaging

Musical Sound

♫♪♫♩♪♬♫♩♬

-Noise has no pattern.

-Music has a pattern and deliberate pitches.

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

The Doppler Effect

-The change in pitch due to a moving wave source.

Objects moving toward you can cause a higher pitched sound.

Objects moving away you can cause a lower pitched sound

-Used in radar by police and meteorologist and in astronomy.

Sound:Frequency and Pitch

-High frequency means more vibrations hitting the ear.

. Pitch-how high or how low a sound seems to be.

-Healthy humans can hear from 20 Hz to 20,000 Hz

Ultrasonic Sound-has a frequency greater than 20,000 Hz

Infrasonic Sound-has a frequency below 20 Hz

; they are felt rather than heard.

Sound: How We Hear

a)outer ear collects sound

b)middle ear amplifies sound

c)inner ear converts sound

*Speed of sound-332 m/s in air at 0 degrees C.* 

Threshold of hearing-0db

Threshold of pain-120db

Interfering With Waves

Interference-two or more waves overlapping to form a new wave

Constructive Interference(in phase)-sound waves that constructively interfere are louder

Destructive Interference(out of phase)-sound 

waves that destructively interfere are not as loud

Resonance-the ability of an object to vibrate by absorbing energy at its natural frequency.