EarEar

Biology 314Biology 314

Mr. DoronMr. Doron

FeaturingFeaturing

• Function of the ear

• Anatomy of the ear

• Facts and questions / answers

Functions of the EarFunctions of the Ear

• The ear is divided into three parts:

• an external ear,

• a middle ear and

• an inner ear.

• Each part performs an important function in the process of hearing.

• The ear is designed to transfer sound waves from the environment to the brain

External EarExternal Ear

• The external ear consists of the auricle and ear canal.  These structures gather the sound and direct it towards the ear drum

Middle EarMiddle Ear

• The middle ear chamber lies between the external and inner ear

• Consists of three small bones or ossicles (the hammer, anvil and stirrup)

• These structures transmit sound vibrations to the inner ear. 

Inner EarInner Ear• The inner ear is a fluid filled cavity in the

temporal bone

• Inner ear contains the semicicular canals and the cochlea

• The cochlea contains the nerve ending for hearing

Anatomy of the EarAnatomy of the Ear

Auricle

Anatomy of the EarAnatomy of the Ear

• Excellent website below that features the ear with interactive slides…

• http://www.wisc-online.com/objects/index_tj.asp?objid=AP1502

Chain Reaction Involved in HearingChain Reaction Involved in Hearing• The ear registers the sound waves or

stimuli but the brain interprets them and produces the sensation of hearing

EarSounds

cochleaReceiver

Auditory Nerve

Transformer

AnalyserBrain

Conductor

HEARING

Stimuli

Tips for Good HearingTips for Good Hearing• Remove the wax!

– Use Q-tips everyday but be gentle– Do not force entry and hit the ear drum

• Exercise caution when diving – If you swim very deep, go slowly. This allows time for

the Eustachian tubes to equalize the pressure on the two sides of their eardrums

• Avoid high pitched sounds – Human ear can perceive sound with frequency

ranging from 16-16000 vibrations per second. The higher the note, the higher the frequency. High pitched sounds can desensitize you to low pitched sounds causing hearing loss. Middle C on piano = 256 vibrations / second; C one octave higher = 512; scratching nails on the blackboard ?!?

Tips for Good Hearing Tips for Good Hearing

• Avoid loud sounds– 80 dB (decibels or less). Easy on the i-pods. If

I can hear it coming out of your ears, it is too loud. This can cause damage to your eardrum (too much vibration) and cause hearing loss in the long term (ringing of the ears the following day is a sign that your ears are telling you that the noise was too loud! Be careful…)

Tips for Good Hearing Tips for Good Hearing

• Prolonged or repeated exposure to sound levels of over 75 db can cause an irreversible hearing loss.

• This loss often develops without the person affected being aware of what is happening

Notice number of decibels of various sounds on p264 of textbook

QuestionsQuestions

• Part of the ear that houses nerve ending for hearing?

• Inner ear

• Purpose of ear wax?

• Traps foreign particles from entering the inner ear

• Not too much though! Again, use Q-tips gently.