Human ear

The ear is the organ that detects sound.
It not only receives sound, but also aids in balance and body position.
The ear is part of the auditory system.
It has external, middle, and inner portions.
The outer ear is called the pinna and is made of ridged cartilage covered by skin.
Sound funnels through the pinna into the external auditory canal, a short tube
 that ends at the eardrum (tympanic membrane).

Human Ear:
The human ear has three main sections, which consist of the outer ear, the middle ear, and the inner ear.
Sound waves enter your outer ear and travel through your ear canal to the middle ear.
The ear canal channels the waves to your eardrum, a thin, sensitive membrane stretched tightly over the entrance to your middle ear.
The waves cause your eardrum to vibrate.

The human ear can respond to minute pressure variations in the air if they     are in the audible frequency range, roughly 20 Hz - 20 kHz.
It is capable of detecting pressure variations of less than one billionth of atmospheric pressure.
The threshold of hearing corresponds to air vibrations on the order of a tenth of an atomic diameter.
This incredible sensitivity is enhanced by an effective amplification of the sound signal by the outer and middle ear structures.
Contributing to the wide dynamic range of human hearing are protective mechanisms that reduce the ear's response to very loud sounds.
Sound intensities over this wide range are usually expressed in decibels.

It passes these vibrations on to the hammer, one of three tiny bones in your ear.
The hammer vibrating causes the anvil, the small bone touching the hammer, to vibrate. The anvil passes these vibrations to the stirrup, another small bone which touches the anvil.
From the stirrup, the vibrations pass into the inner ear.
The stirrup touches a liquid filled sack and the vibrations travel into the cochlea, which is shaped like a shell.
Inside the cochlea, there are hundreds of special cells attached to nerve fibers, which can transmit information to the brain. The brain processes the information from the ear and lets us distinguish between different types of sounds.


The human ear can perceive frequencies from 16 cycles per second, which is a very deep bass, to 28,000 cycles per second, which is a very high pitch.
Bats and dolphins can detect frequencies higher than 100,000 cycles per second.
The human ear can detect pitch changes as small as 3 hundredths of one percent of the original frequency in some frequency ranges.
Some people have "perfect pitch", which is the ability to map a tone precisely on the musical scale without reference to an external standard.
It is estimated that less than one in ten thousand people have perfect pitch, but speakers of tonal languages like Vietnamese and Mandarin show remarkably precise absolute pitch in reading out lists of words because pitch is an essential feature in conveying
the meaning of words in tone languages.
The Eguchi Method teaches perfect pitch to children starting before they are 4 years old. After age 7, the ability to recognize notes does not improve much.