Audiology

=Audiology= Standards: III-B, III-C, III-D

Prevalence statistics 83 of 1000 children have an educationally significant hearing loss approximately 30% of children who are HOH have another disability as well In adults (USA): 18-44 years=5% 45-64 years=12% 65-74 years=20% 75+ years = 30% !!!

eval hearing sensitivity, determine hearing handicap, ABR, ENG, neonatal hearing screening, otoscopic exam, cerumen (earwax) management, fitting hearing aids, dispensing hearing aids, interoperative monitoring, vestibular testing and treatment, hearing conservation, aural rehabilitation, educational programming
 * Audiology Scope of Practice**

Anatomy: Structure and Function of the Hearing Mechanism
OUTER EAR Structures: Functions: MIDDLE EAR Structures: Functions: INNER EAR and CENTRAL AUDITORY PATHWAY Structures: Functions:
 * Auricle or Pinna (see below)
 * Ear Canal or External Auditory Meatus
 * to "catch" the sound waves and funnel them to the tympanic membrane
 * amplifies high frequency sounds (natural resonance of structures--see more about resonance in Acoustics)
 * Protection--cerumen and hairs keeps out dust and other creepy crawlies
 * Localization
 * Ear Drum or Tympanic Membrane
 * Ossicles
 * Malleus (or hammer)
 * Incus (or anvil)
 * Stapes (stirrup)
 * Eustachian Tube
 * Tensor tympani (muscle attached to the malleus)
 * Stapedius (muscle attached to the stapes)
 * overcome impedance mismatch (between air pressure and fluid pressure inside cochlea)
 * ratio of surface area of tympanic membrane to footplate of stapes increases 24.6 dB
 * lever system (malleus to incus) increases about 2 dB
 * Pressure equalization and drainage through eustachian tube
 * Protection--reflex to extremely loud noises, muscles tense to decrease noise by 15-20 dB
 * Semicircular canals
 * Cochlea
 * Round window and Oval window
 * Base vs Apex
 * Helicotrema
 * Scala Media, Scala Vestibuli, Scala Tympani
 * Reissner's membrane, basilar membrane, tectorial membrane
 * outer and inner hair cells
 * rods and tunnel of Corti
 * Stria vascularis
 * Recticular lamina
 * Spiral ligament
 * Spiral ganglion
 * Habenula perforata
 * Cranial Nerve VIII
 * Cochlear nucleus
 * Superior olivary complex
 * Lateral lemniscus
 * Inferior colliculus
 * Medial geniculate body
 * Auditory cor tex
 * sense receptors for balance (semicircular canals)
 * sense receptors for hearing (hair cells)
 * convert mechanical energy of soundwave into electrical impulses that the nervous system can understand
 * transmit electrical information to auditory cortex
 * mediate simple acoustic reflexes

Pathologies
OUTER EAR MIDDLE EAR COCHLEAR Prenatal: High risk factors: STORCH Postnatal diseases
 * Microtia--small or deformed pinna
 * Anotia--absent pinna
 * Atresia--absence/closure of ear canal
 * Stenosis--narrowing of canal
 * Collapsed canal (usually in older people)
 * Presence of foreign bodies/impacted cerumen
 * tumor
 * external otitis (swimmer's ear)
 * myringitis (inflammation of ear drum)
 * Tympanosclerosis--thickening/scarring of TM, usually from PE tubes or infection
 * Hemotoma--growth of blood clot
 * Exotoses--hard body growth ot the ear canal
 * Otalgia--earache
 * Otorhea--ear drainage
 * Osteomos--spongy bony growth
 * Ossicular chain injuries
 * otosclerosis--stiffening of bone--fixation of stapes footplate in oval window
 * Middle ear infection
 * otitis media
 * chronic otitis media
 * acute mastoiditis (infection in mastoid bone)
 * cholesteatoma--cancerous
 * Siphilis--sev-pro bilat
 * Toxoplasmosis--mod-sev bilat
 * other
 * Rubella--pro bilat
 * Cytomegalovirus--mild-pro bilat
 * Herpes simplex--mod-sev uni or bilat
 * Bacterial meningitis--SN or conductive
 * Mumps--unilat HF
 * Measles--bilat HF SN
 * Herpes--sev bilat HF
 * Meniere's disease--progressive fluctuating SN. fullness, dizziness
 * Ototoxic drugs "mycin" "quinine" "asprin" mod-sev HF SN
 * Noise induced hearing loss
 * Presbycusis--related to old age

Testing
 * Otoscopic examination
 * observe status of canal, ear drum, fluid in middle ear
 * Pure-tone audiometry
 * air conduction
 * procedure: start at about 30dB at 1000Hz, down 10, up 5 until three similar responses are observed; continue to 2kHz, 4kHz, and 8kHz; recheck at 1000Hz; continue to 500Hz and 125Hz; test any interoctaves if more than 20dB gap
 * bone conduction
 * similar to AC, but less frequencies
 * masking
 * if 10 dB or more difference between AC
 * if 40 dB air bone gap
 * 0-2 years old: use visual reinforcer, see if they can localize sound, sound field audiometry (do the detect the sound at all--frequency specific not ear specific)
 * 2-5 years old: conditioned play, tangible/visual reinforcement, conventional testing
 * Speech Reception Threshold
 * like pure-tone, except with speech (spondees--familiarized with two syllable, equal stress, baseball, hotdog) as the stimulus
 * should correspond with the Pure Tone Average (avg of 500, 1000, 2000Hz)
 * may have to use Fletcher's Avg if octave drop of 20 dB or more, Avg two better readings
 * Word Recognition Score
 * at comfortable hearing level 30dB above SRT, percentage of words recognized (monosyllabic, phonetically balanced)
 * Immittance/Tympanography
 * determines functioning of the tympanic membrane, middle ear fluid, eustachian tube fx
 * Type A: normal (peak between -100 and +50)
 * Type A sub S low peak--tympanosclerosis, otosclerosis
 * Type A sub D peak off the chart--flabby TM, dislocated ossicular chain
 * Type B Flat--hole/tube in ear drum, block of wax
 * Type C peak in outlying areas--oncoming/resolving otitis media, poor eustachian tube fx
 * Otoacoustic emissions (OAEs)
 * test of acoustic emissions to determine possible hearing loss, does not require response by patient
 * Auditory Brainstem Response (ABR)
 * medical procedure to test response of hearing mechanism at level of brainstem

Hearing loss can be defined by: So...when I was little, one of my favorite books was called __Pickle Things__ and one of the lines from it was: Pickle things you never see like pickles on a Christmas tree. Pickle ears, pickle nose, pickle hair and pickle toes....Ever fly a pickle plane through pickle snow and pickle rain... Anyway... I went on that little tangent to tell you...
 * Type: Conductive, Sensorineural, Mixed
 * Degree: Normal (0-20dB) Mild (20-40dB) Moderate (40-55) Moderate-Severe (55-70) Severe (70-90), Profound (90+)
 * Configuration:
 * Flat: within 20dB across all freq
 * Rising: Low Freq at least 20dB lower than HF
 * Sloping: HF at least 20dB lower than LF
 * Low Frequency: Loss is restricted to LF range
 * High Frequency: Loss is restricted to HF range
 * Precipitous: Steeply sloping HF loss of at least 20dB per octave

Things you should never see on an audiogram!!
Bone conduction that is better that air conduction An air bone gap of more than 40 dB without masked symbols Pickles... unless someone wanted to get creative and draw a speech pickle instead of a speech banana a red X or blue O an AC difference of more than 20dB between octaves without an interoctave reading given if possible a bone conduction symbol at 8000Hz

Preventing NIHL
 * Turn it down (music, stereo, tv, etc)
 * Walk away (put distance between you and the sound source)
 * Wear earplugs

__**Amplification**__ Why:
 * improve communication status--make sounds louder, improve speech intelligibility
 * increase signal to noise ratio

Hearing Aids Click here more info on [|Hearing Aids] Components and How it works CROS BICROS
 * A microphone picks up sound from the environment and converts it into an electrical signal, which it sends to the amplifier.
 * omnidirectional--amplifies all sound (from all directions) the same
 * directional--amplifies signal from right in front of the speaker more than sound from behind
 * A amplifier increases the volume of the sound and sends it to the receiver.
 * A receiver (speaker) changes the electrical signal back into sound and sends it into the ear.
 * A battery provides power to the hearing aid.
 * volume control
 * telecoil (for talking on the phone)
 * on/off switch
 * put microphone on bad/dead ear, that transmitts to receiver on good ear, sound goes in good ear
 * put microphone on bad/dead ear, that transmits to receiver on "aidable" ear, amplify sound, sound goes into "better" ear

Conventional-analog/digitally programmable analog Digital Types BTE (Behind the Ear) ITE (In the Ear) ITC (in the Canal) CIC (Completely in the Canal) BAHA See more info on the [|BAHA] A bone anchored hearing aid that utilizes bone conduction route to hearing for people with a conductive component to their hearing loss (absent or deformed pinna, blocked or damaged middle ear)
 * ok for mild loss
 * widely used
 * inexpensive
 * BUT>>>susceptible to interference, limited processing, limited setting
 * better signal to noise ratio, complex processing, clarity, integrity of components
 * BUT>>>expensive

Cochlear Implant See this link to learn about [|cochlear implants] For people with severe-profound hearing loss who get minimal benefit from hearing aids A microphone sends sound wave information to a processor (the gray part, sometimes the processor is body worn) the processor analyzes the signal and sends the information (through the magnetic round portion) to the electrode, which is wound through the cochlea which essentially takes the place of the hair cells, which stimulates the auditory nerve and the message is sent to the brain. However, as noted on the site, a cochlear implant is not a magic fix, it requires a lot of dedicated work in speech and listening therapy (which is where we come in).

References [|www.britannica.com/ EBchecked/topic-art/431888] __h__ ttp://instruct.uwo.ca/anatomy/530/audipath.gif www.uvm.edu/cmsi/luse/ images/ear-anatomy.jpg http://download.videohelp.com/vitualis/med/diagram_of_cochlea.htm http://virtualmedicalcentre.com http://health.howstuff**works**.com/**hearing**-**aid**.htm http://www.nidcd.nih.gov/health/hearing/coch.asp http://www.nidcd.nih.gov/health/hearing/hearingaid.asp http://products.cochlearamericas.com/baha/introduction-to-baha/introduction-to-baha

Hegde, M.N. (2001). __Introduction to Communicative Disorders, 3rd Edition__. Austin, TX: Pro-Ed Inc. Lee, L. (2005). Lecture notes from SPHI 392: Introduction to Audiology, Eastern Michigan University. Lee, L. (2008). Lecture notes from SPSI 578: Audiometric Testing, Eastern Michigan University.