audiology midterm

adult audiology

*ENT practice, VA hospital, military audiology, teaching and general hospitals, private practice

pediatric audiology

children’s hospitals, schools, private practice

teachers, preceptors, mentors

university faculty, off campus clinics, research labs

educational audiology

private, public, schools for deaf

industry

research, sales, training

father of audiology

raymond carhart

james jerger

developed clinical tests for accurate diagnosis of HL; Carhart’s student

CC Bunch

established audiology program and advanced quality of practices

1960s-70s

new techniques of diagnosing HL, early identification of eighth nerve tumors, start of private practices and hearing instrument dispensing

mother of pediatric audiology

Marion Downs

1980s-90s

expanded scope of practice; vetibular testing, digital signal processing, use of computers, universal newborn hearing screening, and intraoperative monitoring

licensure

required to practice and requires continued education, must follow scope of practice and code of ethics

certification

generally optional, ASHA and ABA-AAA; certifications in specialties like peds and CI, requires CEUs (30 hours every 3 years)

audiologists work with

SLP, OT, neurologists, genetic specialists, opthamology, psychologists, therapists

educational credential

must get a clinical doctorate (AuD)

sound

generated by vibrations and is carried through the air through pressure waves

frequency is physical

pitch is perceptual

intensity is physical

loudness is perceptual

frequency

how often an event occurs in a given time (Hz)

intensity

how far a body vibrates from its original resting point

dB SPL (sound pressure level)

physical measurement for sound waves propagating through the air; used when verifying hearing aids/other devices with HL

dB HL

how sound is described for most hearing test procedures performed in an audiology clinic; used as audiometric zero

dB SL (sensation level)

sound is described in terms of SL as an indicator of a specific patient’s hearing level; sound presented at an intensity level that is a certain number of dB over a patient’s referenced threshold

minimal auditory pressure

thresholds are auditory thresholds measured with pure tone signals with the listening in a sound treated room and wearing earphones; monaural

minimal auditory field

thresholds are auditory thresholds measures with the listener in a sound treated room facing a loudspeaker; binaural (unless there is a difference in between ears)

difference between MAP and MAF in lower freq

due to masking spectrum of vascular noise

difference between MAP and MAF in higher freq

due to different resonant characteristics in the outer ear

psychoacoustics studies

the sensations associated with frequency, intensity, and duration

temporal integration

describes the relationships between duration of sound and its detection by the auditory system of the listener

duration has/has no effect on the threshold for sounds lasting longer than 1 sec

no

there is progressively poorer/stronger detection associated with sound durations of less than 1 second

poorer

greater intensity is needed for detection of

brief sounds

audiometer

plays calibrated pure tone signals via transducer options at a specific intensity level

hearing threshold

Softest intensity level (dB) that generates a
response from the patient 50% of the time

sound treated room

quiet, audiometer outside; mic and visible patient inside

ANSI

yearly calibration method; defines standards for output levels in dB SPL that correspond to audiometric zero (0 dB HL)

biologic calibration

daily; listening to check of equipment

PTA transducers

AC: supraaural earphones, insert earphones, loudspeakers; BC: bone vibrator; circumaural earphones for ultra high freq

behavioral audiometry

subjective; person being tested responds to sound with some type of behavior

factors that can influence testing

age, cognitive factors, motivation, attention, way instructions are presented/interpreted

patient responses

button pressing, raising hand, verbal, pediatric (sucking, head turn, blinking, putting block in bucket, eye opening)

false negative

no response when audiologist believes tone was audible to patient

false positive

response when there was no tone present

reducing false responses

reinstruction, vary time between audible tones, pulsing or warbling tone, pulse counting procedure

step size between intensity levels in clinical audiometry

5 dB

test frequencies for AC

250-8000 Hz

test frequencies for BC

500-4000 Hz

pure tone threshold measurement

start with AC in better hearing ear, test both AC and BC, use Hughson westlake method

Hughson Westlake method

response = move down 10 dB, no response = move up 5 dB, until 2/3x ascending run response

test retest reliability

within 5 dB

other PTA options

method of limits, method of adjustments (continuous sound), method of constant stimuli

PTA BC

placed on temporal bone mastoid or forehead, use same methods for obtaining threshold, some responses may be vibrotactile esp in low freqencies (marked with V)

three mechanisms of BC

osseotympanic, inertial, distortional

osseotympanic

bone oscillation causes changes in air pressure; waves travel through EAC like AC waves

inertial

movement of the skull also makes ossicles move and vibrates stapes against the oval window

distortional

when exposed to vibration, bones become distorted and in turn distort structures within them like the cochlea

to determine HL type

must test both AC and BC

pediatrics behavioral testing

behavioral observation audiometry, visual reinforcement audiometry, tangible reinforcement operant conditioned audiometry, conditioned play audiometry

behavioral observation audiometry (BOA)

6-8 months, usually 2 clinicians, child in caregiver lap in soundfield, look for behavioral response with stimulation (noisemaker, cellophane, toys)

major limitations of BOA

responses too variable, examiner judgment is influenced by bias, habituation

localization

occurs by 8 months, hearing thresholds must be similar in each ear for sound to be localized, localization matures: eye and head horizontal, vertical, on arc, then straight to sound source

visual reinforcement audiometry

6 mo to 2 years, active listening apparent, localization response to stimuli and reinforces head turn with visual stimuli (animated video, toy, or light)

tangible reinforcement operant conditioned audiometry (TROCA)

used for people with developmental disabilites, children that are hard to test, or CI programming, reinforce with small treat when they press button as they hear noise

conditioned play audiometry (CPA)

peg on pegboard, block in bucket, trains child to listen to stimulus and respond by motor response, interest, motivation and headphone acceptance, must watch for false positives, multiple sessions needed, can be performed in soundfield

no masking AC RE

O

no masking AC LE

X

no masking BC RE

<

no masking BC LE

>

masking BC RE

[

masking BC LE

]

Pure Tone Average

add AC thresholds at 500, 1000, 2000 Hz and divide by 3

normal hearing

less than 15 dB

slight HL

16-25 dB

mild HL

26-40 dB

moderate HL

41-55 dB

moderately severe

56-70 dB

severe

71-90 dB

profound HL

>90 dB

conductive HL

abnormal AC, normal BC

mixed HL

abnormal BC, abnormal AC, presence of ABG equal to or greater than 15 dB

sensorineural HL

no ABG, abnormal BC, abnormal AC

retrocochlear HL

hearing loss beyond the cochlea, neural

ipsilateral masking

test signal and masker are presented to same ear

contralateral masking

test signal and masker are presented to different ears

why mask?

to ensure that the test ear is the only one responding, contralteral masking is usually applied to the NTE

crossover and cross hearing occur by

BONE CONDUCTION

Interaural attenuation

the reduction of sound intensity as it travels from one ear to the other

shadow curve

false hearing that is caused by cross hearing

IA by TDH phones (AC)

40 dB

IA by BC

0 dB

IA for deeply inserted phones is greater in low frequencies because

reduced occlusion effect

Air Conduction Masking formula

AC(TE) - BC(NTE) > IA

Bone Conduction Masking formula

ABG(TE) > 15 dB (contralateral masking is required when it is greater than 15 dB)

occlusion effect

occurs when ears are covered by inserts/earphones; results in false but measurable improvement in BC threshold, must account for OE when masking BC with NH or SNHL

effective masking

masking noise adequately prevents crossover

efficient masking

use minimum amount of noise necessary to mask NTE

if the noise power is less than the tone power

the patient can still hear the tone

if the noise power is greater than the tone power

the tone becomes inaudible/masked

broadband noise

contains a wide range of frequencies (white noise)

critical band

narrow range of frequencies around a pure tone that contribute to masking it; bandwidth of critical band increases with frequency