The Human Ear and Hearing

Sound concept research projectBy Alice Gold

The Human EarThe human ear is sensitive and responds to different

pressure variations.

When variations arrive in the ears of the listener, the sound pressure waves are collected in the outer canal of the ear. (Pinna)

The sound waves are then changed into mechanical vibrations.

There are 3 bones in the ear that act as an amplifier and a limiting device.

These bones are called the “hammer”, the “anvil”, and the “stirrup”.

The Human Ear The “Amplifier” significantly increases the vibrations

that are transmitted from the eardrum.

The “Protection Device” reduces the level of loud, transient sounds.

The vibrations are then applied to the inner ear (called the Cochlea), which contains 2 fluid filled chambers.

There are tiny hair receptors that respond to certain frequencies depending on their placement in the ear.

The result in the neural stimulation gives us the sensation of hearing.

HearingThe threshold of hearing: the minimum sound

pressure that produces the phenomenon of hearing in hearing in most people. It equals 0.0002 microbars.

One microbar is equal to 1 millionth of normal atmospheric pressure.

This shows how sensitive the ear is.

0 dB SPL is defined as the level that an average person can hear at a specific frequency only 50% of the time.

HearingThe threshold of feeling: an SPL that causes

discomfort in a listener 50% of the time.

It occurs at a level of about 118 dB SPL between the frequencies of 200 Hz and 10kHz.

HearingThe threshold of pain: the SPL that causes pain

in a listener 50% of the time.

It corresponds to an SPL of 140 dB in the frequency range between 200 Hz and 10 kHz.

Hearing loss Hearing loss generally occurs when the hair/nerve

combinations are damaged or as they deteriorate with age.

To take care of your hearing you should:

1. Avoid hazardous sound environments.

2. (if thais not possible) Wear hearing protection devices (foam ear plugs, custom-molded ear plugs, or in-ear monitors.)

3. Monitor the sound-pressure levels at around 85 dB.

4. Take 15 minute “quiet breaks” every few hours.

5. Avoid practicing at concert-hall levels.

6. Have your hearing checked periodically by an audiologist.

Hearing lossDifferent types of hearing loss:

Acoustic trauma: when the era is exposed to sudden, loud noises in excess of 140 dB.

Temporary threshold shift: temporary hearing loss due to long-term loud noises.

Permanent threshold shift: loud noises in a specific or broad hearing range can lead to permanent hearing loss in that range.

Human Audio Spectrumhttp://www.youtube.com/watch?v=qNf9nzvnd1k