The auricle is the external, lateral paired structure. Its function is to capture and transmit
sound to external acoustic meatus.

Outer ear - Air
 Middle ear - Mechanical
 Inner ear - Liquid
 Brain

Conductive and sensorineural

Rinne and weber tests

Conversation may become less fluid
 Interaction in noisy places can become problematic
 Your personality may change as you adjust
 Difficulty distinguishing sounds, sometimes seeming to others like you are ignoring
them
 Isolated, partaking in fewer social activities
 Intimacy issues, with feelings of inadequacy
 Problems getting on at work
 Sexual issues

Bony labyrinth, Membranous labyrinth

Air transmitted sound waves are directed toward the delicate hearing mechanisms
with the help of the outer ear, first by the pinna, which gently funnels sound waves
into the ear canal, then by the ear canal.

Sensorineural is irreversible and conductive may not be

1. The doctor strikes a tuning fork and places it on the middle of your head
2. You note where the sound is best heard - The left ear, the right ear, or both equally

 Feelings of anger
 Low confidence, especially in social settings
 Frustration
 Depression
 Difficulty concentrating, for example when communicating
 Embarrassment
 Short-tempered and less tolerant towards others
 Mistrustful of others

Stapes, Malleus, incus

When air movement strikes the tympanic membrane, the tympanic membrane or
eardrum moves.
 At this point, the energy generated through a sound wave is transferred from a
medium of air to that which is solid in the middle ear.
 The ossicular chain of the middle ear connects to the eardrum via the malleus, so
that any motion of the eardrum sets the three little bones of the ossicular chain into
motion.

Conductive hearing loss is the result of sounds not being able to pass freely to the inner ear.
This can be caused by problems such as:
 Infection
 Buildup of earwax
 Punctured eardrum
 Fluid in the middle ear
 Damage to the small bones within the middle ear
The result of this type of hearing loss is that sounds become quieter, although not usually
distorted. Depending on its cause, a conductive hearing loss can either be temporary or
permanent.

1. Doctor strikes a tuning fork and places it on the mastoid bone behind one ear
2. When you can no longer hear the sound, you signal to the doctor
3. Then, the doctor moves the tuning fork next to your ear canal
4. When you can no longer hear that sound, you signal to the doctor
5. The doctor records the length of time you hear each sound

466 mil

 Central part of the bony labyrinth.
 It is separated from the middle ear by the oval window, and communicates anteriorly with the cochlea and posteriorly with the semicircular canals.
 Two parts of the membranous labyrinth, the saccule and utricle, are located within the vestibule Cochlea
 Houses the cochlea duct of the membranous labyrinth (auditory part of the innerear)
 Twists upon itself around a central portion of bone called the modiolus, producing acone shape
 Extending outwards from the modiolus is a ledge of bone known as spiral lamina, which attaches to the cochlear duct, holding it in position.
 The presence of the cochlear duct creates two perilymph-filled chambers above and below_
 Scale vestibuli - Located superiorly to the cochlear duct. It is continuous with the vestibule.
 Scale tympani - Located inferiorly to the cochlear duct. It terminates at the round window.Semicircular canals_
 There are three semicircular canals - Anterior, lateral and posterior
 They contain the semicircular ducts, which are responsible for balance along with the utricle and saccule

The ossicular chain transfers energy from a solid medium to the fluid medium of the
inner ear via the stapes.
 The stapes is attached to the oval window.
 Movement of the oval window creates motion in the cochlear fluid and along the
Basilar membrane.
 Motion along the basilar membrane excites frequency specific areas of the Organ of
Corti, which in turn stimulates a series of nerve endings.

Sensorineural hearing loss
This type of hearing loss is sometimes referred to as sensory, cochlear, neural, or inner ear
hearing loss.
A permanent sensorineural hearing loss is the result of damage to the hair cells within the
cochlea or the hearing nerve (or both).
Damage to the cochlea occurs naturally as part of the ageing process (presbycusis), but
there are many things that cause sensorineural hearing loss, or add to it, such as:
 Regular and prolonged exposure to loud sounds
 Ototoxic drugs
 Certain infectious diseases e.g. Rubella
 Complications at birth
 Injury to the head
 Benign tumours on the auditory nerve
 Genetic predisposition
Sensorineural hearing loss not only changes our ability to hear quiet sounds, but also
reduces the quality of the sounds that is heard, meaning that individuals with this type of
hearing loss will often struggle to understand speech.
Once the cochlea hair cells become damaged, they will remain damaged for the rest of a
person's life, therefore sensorineural hearing loss is irreversible and cannot be cured

 Normal hearing will produce equal sounds in both ears
 Conductive hearing loss - Sound to be heard best in abnormal ear
 Sensorineural hearing loss - Sound to be heard best in normal ear

60%

The membranous labyrinth is a continuous system of ducts filled with endolymph. It lies
within the bony labyrints, surrounded by perilymph. It is composed of the cochlear duct,
three semicircular ducts, ssaccule and the utricle.
Cochlear duct:
 Situated within the cochlea
 Organ of hearing - Houses the epithelial cells of hearing, the organ of corti
Saccule and utricle:
 Two membranous sacs located in the vestibule
 Endolymph drains from the saccula and utricle into the endolymphatic duct, the duct
travels through the vestibular aqueduct to the posterior aspect of the petrous part of
the temporal bone, here the duct expends to a sac where endolymph can be
secreted and absorbed

Semicircular ducts:
 Located within the semicircular canals, and share their orientation
 Upon movement of the head, the flow of endolymph within the ducts changes speed
and/or direction
 Sensory receptors in the ampullae of the semicircular canals detect this change, and
send signals to the brain, allowing for the processing of balance

With the initiation of the nerve impulses, another change in medium occurs: from
fluid to neural.
 Nerve impulses are relayed through the CN8 through various nuclei along the
auditory pathway to areas to the brain.
 It is the brain that interprets the neural impulses and creates a thought, picture, or
other recognized symbol.

Conductive:
Infection
 Buildup of earwax
 Punctured eardrum
 Fluid in the middle ear
 Damage to the small bones within the middle ear

Sensorineural
Regular and prolonged exposure to loud sounds
 Ototoxic drugs
 Certain infectious diseases e.g. Rubella
 Complications at birth
 Injury to the head
 Benign tumours on the auditory nerve
 Genetic predisposition

 Normal hearing will show an air conduction time that is twice as long as the bone
conduction time
 Conductive hearing loss - Bone conduction is heard longer
 Sensorineural hearing loss - Air conduction is heard longer but may not be twice as
long

 Work - May struggle finding a job
 Doorbells - Can get visual doorbells, extra-loud doorbells, and portable doorbells
 Phones - There are extension chimes for telephones to give out louder noises and
many can replace sound with a visual flash
 Theatre and cinema - Audio enhancement is available at many
 Televisions - There are customised televisions e.g. subtitles, portable equipment
 Alarms - Can use light instead of sound