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