What are some practical ways we use sound energy?
The Human Ear
IntroductionYour ear converts sound
waves into nerve impulses that your brain interprets.
Parts of the Ear The Outer Ear
Contains the pinna, ear canal and ear drum
The Middle EarContains three bones: hammer, anvil
& stirrup The Inner Ear
Contains the cochlea and auditory nerve
The Outer Ear The pinna is specially shaped to
gather and focus sound waves and direct them into the ear
The ear canal is a hollow tube that carries the sound waves to the ear drum
The sound waves hit the ear drum, causing it to vibrate. The ear drum transmits these vibrations into the inner ear where they are amplified.
The Middle Ear Has the smallest bones in the human
body: hammer, anvil and stirrup Their job is to amplify the vibrations
of the eardrum and transmit it into the inner ear.
The Inner Ear The cochlea is a snail-shaped tube
that is lined with receptors that respond to sound
The receptors are tiny hair cells that shake back and forth in response to sound waves
When they shake, the hair cells create nerve impulses which go to the brain along the auditory nerve
Anatomy of the Human Ear
High vs. Low SoundsHigh pitch sound carry more
energy and travel further into the cochlea
Lower pitch sounds carry less energy and don’t travel as far into the cochlea
Intensity and LoudnessThe intensity of a sound
wave is the amount of energy the wave carries per second through a unit area.
Loudness, or sound level, is measured in decibels (dB)
Sound Loudness (dbs)
Hearing Damage
Average Home 40-50
Loud Music 90-100 After long exposure
Rock Concert 115-120 Progressive
Jet Engine 120-170 Pain
Space shuttle engine
200 Immediate and irreversible
Frequency Frequency is measured in Hertz (Hz) The frequency of a sound wave is the
number of vibrations that occur per second Meaning, a frequency of 50 Hz means fifty
vibrations per second. People hear sounds with frequencies
between 20 HZ and 20,000Hz.
Ultrasound
- sound waves with frequencies above the normal human range of hearing. Infrasound - sounds with frequencies below the normal human range of hearing.
http://www.oprah.com/oprahshow/Dr-Oz-Goes-Inside-the-Human-Ear-Video
http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearing-test/
http://www.noiseaddicts.com/2009/02/hearing-test-hear-like-teenager/
http://www.betterhearing.org/hearing_loss/how_we_hear/virtualeartour.swf
http://video.about.com/pediatrics/Ear-Pressure.htm