Overview of the peripheral auditory system
Hearing Loss
Interpretation of an audiograms
Assistive listening devicess
Cochlear implants
FM system

1.Components of the system
Our peripheral auditory system is subdivided into the outer ear, the middle ear and the inner ear. Below is a brief introduction of each part.

(1)The outer ear
Pinna: It¡¦s the most noticeable part of the auditory system, and its functions include¡X
To protect the outer ear canal;
To collect and channel sounds to the middle ear, and
To help localize sounds by the differences of time and sound level between ear.
Outer ear canal: It opens to the air on one side and ends at the eardrum on the other. The outer 1/3 of the canal is made up of cartilage, and the inner 2/3 bone. The outer ear canal is about 2.5 cm in length, and has the following functions¡X
„c
To clean: The outer part of the canal is lined up with fine hairs that help clean away earwax or tiny foreign objects like dirt.
„c
To protect: The earwax in the auditory canal keeps the canal moist, and protects bugs from entering accidentally and causing harm to the ear.
„c
To resonate: The ear canal resonates sounds within a frequency range from 2500 to 4000 Hz. Therefore, when transmitted into the canal, the 2500-4000 Hz portion of speech would be amplified. It is noteworthy that this frequency range is crucial to speech intelligibility.

(2)The middle ear
Eardrum: After transmitted into the ear canal, sound waves impinge on the eardrum and cause vibration of the eardrum and the ossicles in the middle ear.

The ossicles: The ossicles are composed of malleus, incus and stapes. The malleus is attached to the eardrum. When sounds waves travel to the ear canal and cause the eardrum to vibrate, the ossicles move as well. Sound energy is transformed into mechanical energy in the middle ear, and then transmitted into the inner ear by the impinging movement of the stapes on the oval window of the inner ear.

(3)The inner ear

Cochlea: Over 10,000 hair cells in the cochlea are responsible for receiving and analyzing the sound signal that comes to the inner ear. Here, mechanical energy is converted into hydraulic energy, and later converted into electrical energy by the movement of hair cells. Afterwards, the sound signal passes to the brain through the auditory nerve.
ƒÞ Vestibular system: This system is responsible for our balance.

2.How do we hear?

Sound waves travel in the outer ear canal¡÷ The eardrum vibrates¡÷ The ossicles move¡÷ The stapes pushes the oval window¡÷ The endolymph in the inner ear flows¡÷ Hair cells move accordingly¡÷ Auditory nerve¡÷ Brain