What are some practical ways we use sound

What are some practical ways we use sound energy? The Human Ear

Introduction • Your 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 Ear • Contains 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 Sounds • High 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 Loudness • The 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 (d. B)

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, 000 Hz.

Ultrasound 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/canyou-hear-this-hearing-test/ • http: //www. noiseaddicts. com/2009/02/hea ring-test-hear-like-teenager/ • http: //www. betterhearing. org/hearing_loss /how_we_hear/virtualeartour. swf • http: //video. about. com/pediatrics/Ear. Pressure. htm