Hearing and Balance 3

Threshold

the level of stimulation required to trigger a neural impulse

Auditory Threshold

the quietest sound that a person can hear

AuditoryFactors that affect threshold

Duration of signal, type of signal, noise level in the room, equipment calibration, and earphone type

Ideal duration of signal

1-2 seconds

Non auditory factors that affect threshold

Instruction, psychological state, reinforcement, attenuation step size, patients ability, and timing pattern of presenting signal

What age group is reinforcement most important for

children

Attenuation step size meaning

How you adjust intesity

How could timing pattern affect threshold

If the person learns the timing pattern they may have false positive results

Listening check

Daily verification of the output of audiometers and earphones conducted with a known normal-hearing person. Sometimes called biological calibration.

Otoscopic Examination

the examination of the ear canal and tympanic membrane through the use of an otoscope

When is the otoscopic examination extra important

When using insert earphones

Instructions to patient

Instruct the patient prior to placing earphones

Instructions should be:

brief, uncomplicated, and language appropriate

What should you do if you dont think the patient understood the instructions

Ask them to repeat them back to you

What might you want to ask a patient to remove when placing earphones

glasses and earrings

What must patients always remove

gum

you should place supra-aural earphone when standing ___ the patient

infront of the patient

Where does the diaphragm of the supraaural earphones go

over the opening of the ear canals

What are the advantages of insert earphones

greater ambient noise reduction, improved test-retest, reduction of ear canal collapse, reduced need for masking

Always test the ear that is ____

better

If the patient does not feel one ear is better start with the

right ear

For attenuation go up ___ and down ____

up 5 and down ten

Decrease the intensity of the signal by after the patient gives a correct response

10

Increase the intensity of the signal by ____ after the patient fails to respond

5

The audiogram is in dB __

HL

What is the threshold of a pateint

The lowest dB where the patient responds at least half of the time, with a minimum of two. responses at that level

What type of incorrect response is most common

False positive

False positive

Patient responds when no signal has been presented of the stimulus below threshold

Are false positives normal

Yes

Causes of false positives

Tinnitus, Physiological Noise, Rhythm patterning

Which type of incorrect response is not common

False negative

False negative

The failure of a patient to respond during a hearing test when he or she has in fact heard the stimulus

Causes of false negative

Attempting to exaggerate a hearing loss or poor instructions

Test all octaves between ____ and _____

250 and 8000

When would you test interoctabes

If there is a 20dB or greater difference between adjacent octaves

What frequency do most people start at ?

1000

After you start at 1000 Hz do you go up or down

up

Is air conduction always tested

Yes

Air conduction tests sound as it passes through

the outer, middle, and inner ear

What can air conduction test results tell you

the degree of hearing loss

What can air conduction test results not tell you

The location of the problem

What earphones are used for air conduction testing

insert or over ear

Air conduction testing is _ testing

behavioral

Is bone conduction routinely tested

no

Bone conduction measures the sensitivity of the

inner ear

Bone conduction testing helps you to detemine

The site o fthe earing loss

conductive hearing loss

hearing impairment caused by interference with sound or vibratory energy in the external canal, middle ear, or ossicles

sensorineural hearing loss

hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves; also called nerve deafness

Bone Conduction Oscillator

Secured to the mastoid or forehead, used to stimulate the cochlea directly by vibrating the bones of the skull.

Where should the bone oscillator be placed

Mastoid in adults

Superior posterior temporal bone for infants

Bone conduction signals are loudest from

The mastoid

How to place oscillator on mastoid

Remove hair from the surface

Put the side of the raised round disk against the head

Be sure the oscillator doesn't slide back

Be sure the oscillator doesn't touch the pinna

Put the band over the patient's head

Placing the oscillator on the forehead is shown to be

better

When Placing the oscillator on the forehead there is less participation of the

middle ear

The boney surface of the forehead is more

homogenous

Major disadvantage of forehead placement

You need more intensity to reach threshold

The oscillators are on a

headband

Bone conduction is done with ears occluded or unoccluded

occluded

For bone conduction you cannot test above

4k Hz

Why can you not test above 4K Hz for bone conduction

It is hard to efficiently transduce high frequencies through vibrations

It takes a lot ___ energy to reach threshold by bone conduction than air

more

Masker

The elevation of threshold of one sound by the presence of another

Types of masking

ipsilateral and contralateral

Ipsilateral marking

tone and masker presented to same ear

contralateral masking

tone and marker presented to opposite ears

Why is clinical masking necessary

To make sure the response from the patient is accurate and a valid representation of the hearing sensitivity for the ear being tested

What prevents cross-hearing

clinical masking

clinical masking

contralateral masking

What type of masking is used for air and bone conduction

narrow broad noise

Narrow broad noise is ___ octave wide

1/3

With narrow broad noise you hear ____ in non-tested ear

static

What masking is used for speech audiometry

Speech noise

Speech audiometry

measurement of ability to hear and understand speech

For speech noise you hear static in non tested ear but the static has more _

frequencies

Masked left ear symbol

]

Masked right ear symnol

[

Type of hearing loss

conductive, sensorineural, mixed

Site of lesion

Where the problem is

What do you need to determine type of hearing loss

Bone and ear conduction

What do you need to determine degree of hearing loss

air conduction

Degree of hearing loss

Refers to the severity of hearing loss, which can range from mild, moderate, severe to profound levels

For configuration of hearing loss you need

air conduction

Configuration of hearing loss

The shape and slope of the pure tone air conduction results across the frequencies tested

Is there a universally accepted way to classify degree hearing loss

No

PTA

Pure tone average

PTA serves as ___ of hearing loss

degree

Pure Tone Average

The average of the air conudction thresholds at 500, 1000, and 2000 Hz

The exception for using 3 frequencies for PTA

If there is a 20 dB HL or greater difference between any of the three frequencies, calculate the average using only the thresholds at the 2 better frequencies - that is the 2 frequencies which show the lowest HL threshold.

Normal Hearing`

-10 - 20 dB

Mild Hearing loss

21-40 dB

Moderate Hearing Loss

41-55 dB

Moderate Severe Hearing Loss

56-70 dB

Severe Hearing Loss

71-90 dB

Profound hearing loss

91+ dB HL

Most common form of hearing loss

High frequency sloping