The Outer Ear
The Pinna
Made of skin and cartilagePrimarily for funnelling and locating sound
The Tragus
Helps collect sounds from behind and is an effective noise-blocking mechanism when directed over the ear canal by a finger.
Direction Finders
The subtle delay between a sound arriving at each ear due to the shape of the head and the effect of the pinna folds provide cues to help the brain locate direction.
Help in funnelling sound into the ear canal
Some pinnas have a better chance of funnelling sound than others
Acoustic Hearing Enhancers
History has provided many attempts to enhance sound funnelling. Acoustic 'sound locators' became crucial tools in war to detect an oncoming enemy.
Ear Canal
Otherwise known as the auditory ear canal or external acoustic meatus. The canal is 25mm long, 7mm in diameter, and from above looks like it has a kink in it. Sound is funnelled down the ear/auditory canal to the ear drum which is also called the tympanic membrane.
The ear canal produces a waxy oil called cerumen [si-roo-min] (earwax) as a protective mechanism from dust, foreign particles, micro-organisms (repelled by scent), and fungi while also lubricating the ear canal skin, protecting from irritation. A build-up of wax can dampen sound. This wax should be removed only by an ear nurse. Do not stick cotton buds in the ear canal.
The Ear Drum - The Tympanic Membrane
Conductive Hearing Loss
Like the skin on the ear drum's namesake, the tympani drum, the eardrum wobbles. The eardrum wobbles according to the vibrations collected down the ear canal: 10,000 times per second for a 10kHz tone, and 440 wobbles per second for concert pitch (440Hz).
Our eardrum is sensitive and can detect movement half the width of a hydrogen atom.
Our eardrum is sensitive and can detect movement half the width of a hydrogen atom.
Healthy Eardrum
(tympanic membrane)
Tympani Drum
Perforated Eardrum
A build-up of wax in the ear canal, fluid in the middle ear caused by sickness, or a hole in the eardrum reduces the ability to transfer sound vibrations from outside the body to the inner ear. As with the tear of a percussion drum skin, once perforated sound vibrations are not replicated and are distorted as the skin 'flaps' about.
