CDIS 300 Chapter 2: hearing and ear physiology

audiometer

instrument to measure hearing

outer ear

sound collection, slight signal gain,

1. pinna-shapes frequency compnents

2. external auditory meatus- tunnel/canal

3.tympanic membrane- eardrum

middle ear

impedence matching resists flow of energy to match pressure

1. tympanic membrane

2. ossicles

3.oval window (stepes)

area ratio=oval window impedence matching #1

tympanic membrane to oval window: increase of 25 dB

lever advantage impedence matching #2

increase of 2dB, all ossicles work together,

buckling effect impedence matching #3

buckling of tympanic membrane results in movement of the malleus, increase of 4-6 dB

31

Combined devices have a total of ____dB

Otitis media

disorder of middle ear that has fluid and inflammation

Otosclerosis

bone growths on the ossicles on bones which effects their manners and impedence matching

tumors (glummus, benine, middle ear)

effects hearing and sound recepting, multiple types

inner ear function

frequency and temporal acoustic analysis, analyzes incoming acoustic signal

proprioceptive system (space)

vestibular mechanisim: semi-circular canals-->

horizontal canal

influences head rotation when (no) "YAW)

anterior canal

vertical head movement (yes) "PITCH"

posterior canal

moving head to shoulder, tilt, "ROLL"

Macula

hair cells for linear acceleration

utricle

detects acceleration

saccule

drops in sensation and acceleration

crista ampularis

direction and rate of movement

cupola

tectorial membrane, doesnt respond to gravity but flow of fluid

vertigo

dizziness, visual and vistibular have mismatch

labyrinthitis

inflammation of the inner ear, can cause hearing loss and vertigo

BPPV

benign, sudden onset of vertigo, vertigo in eyes and tinnitus

Menier's disease

rare chronic disorder in which the amount of fluid in the inner ear increases intermittently, producing attacks of vertigo

cochlea

which structure is spectral analysis?

traveling wave

result of ossicles of Tympanic membrane, footplates, effects frequency

in cochlea

where is initiation of electrical events?

cochlea

spectrum analyzer and transducer, depends on sterocilia (on hair cells)

basilar membrane

displaced towards Scala vestibule, hair cells activated, electrical potentials are initiated

hair cells

stimulation of what results in sound converting to electrochemical energy

excitation of outer hair cells

results of shearing effect on cilia

excitation of inner hair cells

results from fluid flow and endolymph turbulence

electrical potential

helps with high hearing sensitivity and sharpness of frequency distributions, resting or standing potentials which voltage potentials difference measured from cochlea

intracellular resting potential

- found within the hair cells

- negative potential difference between endolymph and hair cell of 70 mV

cochlear microscopic potential

-generated by outer hair cells

-summating potential- direct current shift in endochoclear potential

cochlear nucleus

first stage of auditoy pathway, CN VIII

superior olivary complex

brainstem nuclei, motor function and auditory system and perception of sound

inferior colliculus

receives LSO and cochlea nuclus

medial geniculate body

sensory station, final sensory way of brain cell. relays to thalamus which is sensory relay

cerebral cortex

highest level of processing

prenatal development

-at 9 weeks of gestation the three layers of the tympanic membrane are formed

-cochlea begins development at 10-12 weeks of gestation

25 weeks

at how many weeks of gestation can fetus hear sound?

-threshold is 65dB with range of 500-1000 Hz

-adults hear 20-20000hz

-65 db is about normal convo

32 weeks

-malleus and incus ossification complete

-rapid maturation of cochlea and auditory nerve

-initial auditory response by 30 weeks

-tympanic membrane is similar to adult

between 32-35 weeks

-inner and middle ear have fully formed

-hearing threshold 30db with increasing range like wispering

-increasing ability to localize and discriminate

term infants

-localize and discrimate sound

-infants demonstrate prefernece for higher intonation and rhythmic sing song vocalization

-threshold of 20db with range of 500-4000 Hz

presbycusis

age related hearing loss

conductive presbycusis

mechanical transduct system

sensorineural presbycusis

organ of corti

metabolic presbycusis

blood supply

Age related hearing loss (AHL)

40% of older than 75 is most common, spiral ganglion outter hair cell damage

central effects of biological aging (CEBA)

neural structures-cochlea, nuclei, and path.

1. age

2. severity, configuration, type of loss

3. when begin rehab

4. handicap combriorties

4 variables that affect the type and degree of communication disorder

1. final consonants, unstressed sounds

2. vowel differences

3.stressed rate, breath contro,l and pitch

3sounds not heard or more difficult to develop with hearing loss

Form

language! primary content words, omit function words, telegraphiuc

content

language! weak vocab, difficulty with figurative language

Use

language! difficult having conversations, turn taking, inappropriate responses, clarification and repair

Inner Ear: Cochlea, genetic

sensorineural hearing loss occurs in...

outter or middle ear, ear wax, burst eardrum

conductive hearing loss occurs in the....

aural rehabilitation

Reduce or eliminate communication deficits associated with hearing loss

sensory management

target and enhance auditory function

instruction

increase probability of positive outcome from sensory managment

perceptual training

target activity

counseling

quality of life help

goals of auditory training

1. develop ability to recognize speech and signals

2. children with residual hearing

3. amplification (earpiece)

goals for children with hearing impairment- language development

1. expand vocab

2. enhance syntax and prymatics

3. develop narrative skills

4. literacy

goals for speech development

1. increae amount of vocalizations

2. expand phonetics

3. increase speech intellectuability

inflammatory conditions

1. ottis media-ear infection

2. meniers disease- increase pressure

3. labyrinthitis

congenital issues- born with it

1. congenital atresia- absent meatus (no ear canal)

2. Preauricular pits-tags on outside ear

3. Apert syndrome

4. fetal alcohol syndrome

5. cleft palate-dysfunction of auditory tube

traumatic lesions

resulting from an external insult like loud noise or blow to head

neoplastic changes

glomus tumors, hearing loss

otosclerosis

bone disorder, ossicles of middle ear , bony growths

rheumatoid arthritis

conductive hearing loss