CSD 12: Audiology and hearing science

audiology

the study or science of hearing, hearing loss, and balance

involves diagnosis, management, and treatment

scope of practice of an audiologist

identification

assessment and diagnosis

treatment of hearing loss

hearing conversation

intraoperative monitoring

research

degree

AuD

outer ear

pinna: cartilage

external auditory canal: pathway running from outer ear to middle ear

middle ear

tympanic membrane: when sound waves waves reach it they cause vibration

malleus: largest bone in the ear, relays the vibrations of the incoming sound waves produced by the eardrum to the incus

incus: middle of small bones, transmits vibrations from malleus to stapes

stapes: situated between incus and inner ear, transmits sound vibrations from incus to oval window

inner ear

semicircular canals: three small, ring like structures that are sensitive to angular accelerations

cochlea: a single, fluid filled canal that controls hearing functions

auditory nerve

carries info from cochlea to brain

purpose of outer ear

collects sound waves and channels them into the ear canal where the sound is amplified

purpose of middle ear

to transmit sound waves from the external environment to the inner ear

purpose of inner ear

to convert sound waves into electrical energy

purpose of auditory nerve

connects ears to brain

otoscopy

visual examination of the external ear, ear canal, and tympanic membrane

tympanometry

testing the functionality of the middle ear, tympanic membrane mobility

audiogram

present sounds at each frequency at varying intensity levels using both air and bone conduction

patient responds when they hear/believe they hear sound

the quietest sound they hear is called the threshold and is recorded on the audiogram

shapes:

right ear = red round right

left ear = blue X

air conduction

sound travels through the outer, middle, and inner ear

we use circumaural, supra-aural headphones or insert earphones to obtain air conduction thresholds

bone conduction

bypasses the outer and middle ears

direct reflection of inner ear sensitivity

we obtain bone conduction thresholds using a bone oscillator placed on the mastoid bone behind the ear

conductive hearing loss

caused by the pathology in the outer or middle ear

sound info can be carried to the brain but loudness is weakened

bone conduction thresholds are better (low) than air conduction thresholds

sensorineural hearing loss

caused by pathology in the inner ear or auditory nerve

air and bone conduction thresholds are within 10dB of each other

patient experiences both a decrease in loudness and a decrease of speech perception and clarity, especially in noise

generally permanent

can be treated with amplification

mixed hearing loss

bone conduction thresholds are not within normal limits

congenital hearing loss

present from birth, most often sensorineural, genetic, can be caused by injection, injury, or illness in the prenatal, perinatal 28 days postnatal

acquired hearing loss

appears after birth, often due to damage of the outer ear or middle ear

usually temporary if identified and treated

slight to moderate

most common

otitis media

middle ear infection

common cause of acquired hearing loss in children

children’s eustachian tubes are shortened and angled more horizontally making them more susceptible to bacteria and viruses in the middle ear

treated with antibiotics or pressure equalization tubes

2 most common causes of adult hearing loss

age related

acquired