Unit 1 MGT of Hearing Disorders

The National Institute on Deafness and Other Communication Disorders (2021) reported that ____ of adults have some degree of hearing loss by age 75.

half

Sine Waves or sinusoids represent ____ _____. Common stimulus for audiometry is pure tones

pure tones

the reference for dB is

normal human thresholds (softest sound the average human can hear)

0 dB means no sound True or False

false

Hearing sensitivity (threshold) measured in dB Hl is _____

equal across all frequencies

It is possible to hear a sound that is negative dB HL ( true or false)

true but your hearing is better than average

Supra-aural earphones

worn over ear

insert earphones

disposable foam tip is inserted into the ear canal

avoids potential for collapsing ear canal

Bone conduction vibrator

placed on mastoid or forehead

vibrations transferred to the skull, where they are then picked up by the cochlea

Circumoral earphones

used for obtaining extended high frequency thresholds (above 8000 Hz

soundfiled testing

using speakers in the test room to deliver the test signal (no transducer worn by patient) threshold obtained are not ear specific (response will always be from the better ear)

How to reads an audiogram

x-axis frequency

y-axis dB HL

Pure tone stimulus selection

steady tone- pulsed tone (preferred choice) - Warble tone typically used with children or testing low frequencies in sound field

Match?

Falling, Notch, Flat, Rising, Trough(cookie-bite)

Hearing loss is greatest in mid frequencies

Drop at one or two frequencies

Hearing loss is greatest low frequencies

Hearing loss is greatest in high frequencies

Hearing loss is greatest in mid frequencies

unilateral vs bilateral hearing loss

unilateral - hearing loss is present in only one ear, other ear is normal

bilateral- hearing loss is present in both ears

is pulsed or steady tone preferred

pulsed tone, helps with tinnitus identify the tone from the “ringing” they perceive”

warble tone is typically used with

children or testing low frequencies in sound field

Narrow band noise

speech noise

Narrow band noise - used for masking or sound field testing

speech noise - used for masking during speech testing

What can an audiogram tell us

Degree (severity) of hearing loss, type of hearing loss, configuration, unilateral/bilateral, symmetrical/asymmetrical ( are both ears equally affected)

Audiometry is used to determine a patients threshold

softest sound a person can hear at different frequencies

Air conduction testing

sounds presented through the normal hearing mechanism

standard earphones, inserts earphones, or soundfield

easier infection control

collapsing ear canal

AC threshold can tell us the ____ of hearing loss, but alone cannot tell us the type of hearing loss.

ac threshold can tell us the degree of hearing loss, but alone cannot tell us the type of hearing loss.

Bone conduction testing

vibrator headband is places on the mastoid or on the forehead.

must be flat on patients head with correct amount of drove.

Signal sent directly to inner ear bypassing out and middle ear

air conduction threshold first, then bone conduction (BC) threshold testing

Stimulus initially presented at ___

30 dBHL, no response, increase to 50 dBHL, If not heard at 50 dB, sound is increased by 10 dBHL

after sound is initially heard it is down, ___ up.

10 down, 5 up

If patient responds sound is decreased ___

when there is no response sound is increased __

10 dB steps

5 dB steps

AC frequencies

250, 500, 1k, 2k, 3k, 4k, 6k, 8k Hz

what kind of hearing loss is this

AC:

BC:

Air bone gap

Conductive hearing loss

AC abnormal

BC: normal

Air bone gap greater than or equal to 15

What does this audiogram show ?

All thresholds are in the normal range

less than 25 dB HL

Audiogram- shows threshold (softest sound a person can hear) at different frequencies

x-axis: frequency

Y-axis - dB HL

Audiogram symbols

Right air- Unmasked vs masked

left air - unmasked vs masked

right bone- unmasked - masked

left bone - unmasked - masked

soundfield

no response

Masking is important

needed to esnure that the patient is responsing by hearing the tone on the side we are testing

Configuration, unilateral, symmetrical/asymmetrical hearing

air bone gap

reflects how much sound energy is lost as the sound travels through he outer and middle ear

Sensorineural hearing loss is not just attenuation of ____

sound. there is a distortion and makes things sound less clear

Sensorineural hearing loss

caused by dysfunction in the inner ear and or auditory nerve

Problem not just attenuation of the sound

damage to cochlear hair cells

structural or functional problem

distortion

threshold obtained by air and bone conduction will be about the same

Both AC and BC thresholds are poorer than normal and they are within 10 dB of each other

Conductive hearing loss

caused by problems anywhere in outer or middle ear

• BC thresholds are within nomral limits, because there is no problem with cochlea or auditory nerve

• AC threqhols are poorer than monral because there is a problem getting sound to the cochlea through the outer or middle ear.

only considered a conductive hearing loss if there is an air-bone gap of greater than or equal to 15 dB

• sounds are getting to the cochlea but they are not loud enough

what hearinng loss is this . what is SC, BC, air bone gpa

Mixed hearing loss

combination of sensorineural loss and conductive loss in the same ear

• bone air and bone conduction will show a loss

• air conduction will show a greater degree of hearing loss

• both AC thresholds and BC thresholds are poorer than normal AND there is an air bone gap greater than or equal to 15 dB

Speech Audiometry

Pure tone audiograms do not provide direct information about an individual’s ability to understand speech

Speech Audiometry

Process of determing speech understanding speech understandign using speech stimuli

2 possible modes of presentation what are they ? Recorded speech material

played through a CD player, or computer

What is MLV

Monitored live voice ( Clinician speaks into a microphone of the tester side of the sound booth)

Recroded stimulu ensure a ____ and _____ _____.

Recroded stimuli ensure a valid and reliable score.

• Difficult to maintain a consistent volume level when performing MLV

• Children are more engaged by MLV

Common tests for speech audiometry

Speech detection/awareness threshold (SDT/SAT)

speech recognition threshold (SRT)

word recognition score ( WRS)

Speech in Noise testing

Speech detection threshold

lowest level at whcih speech sound can be detected

typiclaly measures for infants or others who cannot provide an SRT

Speech recogniction threshold (SRT)

lowest level at which familiar words can be correctly repeated

uses spondaic words (baseball, cupcake airplane)

The SRT should ____ with pure-tone average (

3-frequency PTA = average ( 500, 1000, 2000 HZ)

2- frequency PTA (less common)= average (500, 1000 HZ)

Word Recognition score (WRS) Word recognition (in quiet)

percentage of CNC words correctly repeated at a suprathreshold stimulus level (typicllay, 40 dB greater SRT)

• Fixed level, that does not change

• Calculated as a percentage correct, not a dB value

what kind of hearing loss is this

AC:

BC:

air bone gap?

Sensorineural hearing loss

AC: abnormal

BC: abnormal

No air-bone gap

Word recognition in noise

• signal-to-noise ratio (SNR) at which 50% of words can be correctly identified

• words are presented at fixed, suprathreshold stimulus level

Purpose of WRS

Provides an estimate of a patients ability to recognize single words at a suprathreshold levels

• used as an estimate of potential benefit from hearing aids

• Can assist in the differential diagnosis of some auditory disorder

What kind of hearing loss is shown?

AC:

BC:

Air bone gap?

Mixed hearing loss

AC: Abnormal

BC: Abnormal

Air bone Gap greater than 15 dB

BOA Behavioral Observation Audiometry

• used for babies that are 0-4 months old

• Observe the baby’s response to a sudden sounds in sound field

BOA

reflexive responses

VRA (Visual Reinforcement Audiometry

at 4-7 months a child is able to turn to look at sounds

at 5-6 months children are good enough at turning their heads

(CPA) Conditioned Play Audiometry

Child is trained to make a certain motor response when a sound is heard (like a game)

Parents should not be in test room

two audiologist

Acoustic Immittance

measure of how well energy moves through the hearing system.

Acoustic Impedance

opposition (resistance) to the flow of sound energy through the system

Acoustic Admittance:

ease of energy flow through the system

Admittance

some vibration passes through (admitted) to the middle ear and go to cochlea

Impedance

some vibration reflected (impeded) into ear canal

Immittance testing allows clinicians to infer the status of the ___ ___ system

middle ear

Pathologies that increase stiffness

• otitis media

• otosclerosis

Pathology that decreases stiffness

disarticulated ossicular chain

For all immittance testing, a probe is inserted into the ear canal to create a ___ seal.

hermetic (air tight)

Changes in pressure result in changes in the _____ component of the middle ear system

stiffness

Intensity of probe tone in the ear canal is measured while the pressure is _____ ____

being changed

Type A Tympanogram

Type As Tympanogram

Type Ad Tympanogram

Type B Tympanogram

Type B with an abnormally large volume

Tm is perforated or a P.E tube is present

Type B with normal volume

Conductive component in the middle ear space

such as otitis media

Type B with an abnormally small volume

Impacted cerumen or foreign object in the ear canal

Type C Tympanogram

Pure Tone Audiogram

Measures hearing sensitivity at different frequencies

Speech detection Threshold (SDT)

Lowest level at which speech sounds can be detected (heard)

Speech recognition threshold (SRT)

measures the lowest level at which a word can be correctly identified

Word Recognition score

percentage of words correctly identifies by the patient at a level well above threshold

OAEs

Reflect outer hair cell health movement

ABR

used to asses the integrity of the auditory nerve. Normal results indicate that a synchronous signal is being sent by the auditory system

Immittance

Tympanometry: measures the mobility of the middle ear system

Acoustic Reflex threshold: measures the lowest intensity that triggers the acoustic reflex

Test Reliability

Refers to whether or not test results obtained are valid. One way we check for this is the relationship between speech recognition thresholds (SRT) and the pure tone average (PTA)

cross checking

looking across multiple tests to ensure the accuracy of all results

Unilateral Conductive Hearing Loss

Good test reliability

Means that the test results are in agreement and are valid

Poor test reliability

• test result may not be completely valid

• We usually say this because tests results are not in agreement

Functional Hearing Loss

• Term used to describe people exhibiting a hearing loss that is not due to an “organic” cause

• Many terms exist to describe patients who exhibit unreliable/inconsistent test result.

If person is deliberately exaggerating HL

• non-organic Hearing loss

• Malingering

• Pseudohpacusis

• Functional Hearing Loss

Problem is at unconscious level

• hysterical

• psychogenic

Should refrain from describing the patient as ____ or ____ hearing loss

malingering or feigning

Words such as ____ are ___ ____ preferred instead

Words such as inconsistent are poor reliability preferred instead

Why would patients want to be diagnosed with a hearing loss

Financial gain, veteran benefits

Patients attempting to fake a hearing loss tend to lack false responses because the sound is actually always easy for them to hear.