VOCAB:

·  Sound

·  Vibration

·  Medium

·  Pitch

·  Amplitude

·  Frequency

·  Doppler Effect

·  Decibel

·  Loudness

·  Infrasonic

·  Ultrasonic

·  Sound produced by vibration, a back-forth motion of an object

·  Travels as longitudinal waves, particles vibrate along a path, high point is called a compression, and low point is rarefaction

·  Ears detect sound waves as electric signals

·  The speed of sound depends on the medium, cannot travel thru a vacuum, but can travel thru S-L-G

·  Outer ear (pinna) acts as a funnel, which leads to the ear canal, eardrum (tympanic membrane), hammer (malleus), anvil (incus), stirrup (stapes)

·  Leads to the cochlea (fluid filled chamber) which make the hair cells vibrate changing the sound energy to electrical energy

·  Speed changes when the medium changes

·  Pitch depend on the frequency

·  If the temperate is colder that the speed of sound is slower

·  1947-Yeager was the first person to travel faster that the speed of sound

·  Pitch – how high or low a sound is be, dependent on frequency

·  High frequency=higher pitch

·  Speed of sound= 340m/s,

·  Avg human can hear b/t 20 Hz and 20000 Hz

·  Infrasonic: under 20 Hz

·  Ultrasonic: any sound over 20 kHz; uses include cleaning jewelry, defrosting car windshields and airplane wings, medical technology, removing kidney stones,

·  As frequency gets higher, the pitch gets higher.

·  Amplitude has a higher sound because of more energy

·  Larger amplitude=larger sound

·  Loudness is how LOUD or SOFT a sound is perceived to be

·  Most common way to express sound: decibel (named after Alexander Graham Bell)

·  Exposure above 85 dB is cause of hearing loss

·  Waves reflect easily off smooth, hard surfaces, odd shapes

·  Echolocation is reflected sound waves to find objects

·  Ultrasonography and SONAR are two uses of technology with echolocation

·  Interference: constructive and destructive

·  Resonance

·  Diffraction

·  Sound barriers

·  Sonic boom