BASIC OVERVIEW OF THE EAR AND HEARING LOSS

The Ear

Video: How We Hear

http://hcd2.bupa.co.uk/fact_sheets/Mosby_factsheets/Hearing_Loss.html

Outer, Middle and Inner Ear

Outer Ear Middle Ear Inner Ear

•Pinna• the visible part of

the outer ear. It collects sound and directs it into the outer ear canal.

•External Auditory Meatus (Ear Canal)• the tube through

which sound travels to the eardrum

•Tympanic Membrane• vibrates when

sound waves reach it

•Malleus (Hammer)• tiny bone that

passes vibrations from the Tympanic Membrane to the Incus

•Incus (Anvil)• tiny bone that

passes vibrations from the Malleus to the Stapes

•Stapes (Stirrup)• tiny bone that

passes vibrations from the Incus to the oval window and then to the cochlea

•Eustacian Tube•a tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside.

•Cochlea• a spiral-shaped,

fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form

•Semicircular Canals•fluid filled tubes attached to the cochlea that help us maintain our sense of balance

•Auditory Nerve• carries electro-chemical signals from the cochlea to the brain

•Brain•processes and interprets signals sent from the ear

Types of Hearing Loss…

There are three types of hearing loss:

Sensorineural

Conductive

Mixed

Sensorineural Hearing Loss

With a Sensorineural loss the inner ear is damaged or not functioning properly

Hearing loss in the presence of a normally functioning outer and middle ear

About 90% of all people with hearing impairments suffer from sensorineural hearing loss

Conductive Hearing Loss

With a Conductive loss the outer or middle ear is damaged or not functioning properly

Hearing loss in the presence of a normally functioning inner ear

Mixed Hearing Loss

A combination of a conductive and sensorineural hearing loss

Both the middle and inner ear are involved

Other Classifications of Hearing Loss

Unilateral Only one ear is

affected

Bilateral Both ears are

affected

Prelingual Hearing loss occurred

before the acquisition of language

Post Lingual Hearing loss occurred

after the acquisition of language. (Usually after the age of two)

Unilateral vs. Bilateral Prelingual vs. Postlingual

Degree of Hearing Loss

Hearing loss can be classified by the following degrees: Mild Moderate Severe Profound

Mild Hearing Loss

A mild hearing loss may cause you to miss 25-40% of the speech signal

Usually this results in problems with clarity Symptoms:

problems understanding someone farther away than a normal distance for conversation

difficulty understanding even up close if the background environment is noisy

weak voices are also difficult to understand for people with mild hearing losses

Moderate Hearing Loss

A moderate hearing loss may cause you to miss 50-75% of the speech signal

Symptoms: problems hearing at short distances difficulty understanding people even face-

to-face difficulty hearing normal conversations problems hearing consonants in words

Severe Hearing Loss

People with severe hearing loss have difficulty hearing in all situations

Speech may be heard only if the speaker is talking loudly or at close range

A severe hearing loss may sometimes cause you to miss up to 100% of the speech signal

Symptoms: inability to have conversations except under

the most ideal circumstances most likely cannot understand any speech

Profound Hearing Loss

Profound hearing loss is the most extreme hearing loss

Symptoms most likely cannot hear any speech at all inability to distinguish even loud

environmental noises Most likely rely on visual cues instead of

hearing as your main method of communication.

Reading an Audiogram•Hearing loss is plotted on an audiogram.

•Right ear is represented by a circle that is sometimes red

•Left ear is represented by An X that is sometimes blue

Frequency and Loudness

Also called pitch Measured in Hertz

(Hz) Shown on an

audiogram from left to right.

Frequencies are lower on the left and become higher as you move to the right

Measured in Decibels (dB)

Show on an audiogram from left to right

Sound is shown as softer at the top and become louder as you move down

Frequency Loudness

Blank Audiogram

The Speech Banana