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 (dB)

SoundLoudness (dbs) Hearing Damage Average Home Loud Music After long exposure Rock Concert Progressive Jet Engine 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.

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