audiology exam 2 review

"up 5 down 10" procedure

after each failure to respond to a signal, the level is increased in 5 dB steps until the first response occurs. After the response, the intensity is decreased 10 dB, and another ascending series is begun.

pure tone threshold

the level at which pure tones of a specific frequency are perceived as barely audible; the lowest intensity level the patient responds to at least 50 % of the time

air conduction routine frequencies

250 Hz through 8000 Hz

bone conduction routine frequencies

250 Hz through 4000 Hz

AC unmasked right ear symbol

O

AC unmasked left ear symbol

X

BC unmasked right ear symbol

<

BC unmasked left ear symbol

>

normal hearing loss

<25 dB HL

mild hearing loss

26- 40 dB HL

moderate hearing loss

41-55 dB HL

moderately severe hearing loss

56-70 dB HL

severe hearing loss

71-90 dB HL

profound hearing loss

91+ dB HL

air bone gap

AC- BC

pure tone average

average of 500, 1000, and 2000 Hz thresholds; useful for predicting the threshold for speech as well as for gaining a gross impression of the degree of communication impact imposed by a hearing loss

masking

process of putting noise into the non test ear (NTE) while measuring responses in the test ear (TE)

crosshearing

reception of a sound signal by the NTE during a hearing test

Why do we need masking?

so the NTE doesn't help out while evaluating the TE

Interaural Attenuation (IA)

as sounds travel from one side of the head to the other, a certain amount of energy is lost in transmission, the difference in the level of a signal delivered to the TE compared to the level of signal that occurs in the NTE

speech threshold test

the lowest level at which speech can be either detected or recognized, similar to PTA except speech stimuli are used

speech recognition test (SRT)

involves the presentation of a speech stimuli at a fixed intensity level above threshold

spondees/ spondaic words

a word with two syllables, both produced with equal stress and effort; often used for speech recognition threshold testing

relationship between SRT and PTA

SRT should be within 10 dB of the patient's PTA; if the difference is more, it could indicate that the patient is exaggerating his pure tone hearing loss

word recognition score (WRS)

an assessment of a patients ability to identify and repeat single syllable words presented at a suprathreshold level

speech banana

distribution of speech sounds at a normal conversational level, ranges from 20 to 50 dB HL

where do consonants generally appear on the speech banana?

generally lower in intensity and higher in frequency

where do vowels generally appear on the speech banana?

generally higher in intensity and lower in frequency

immitance

a measure of how readily a mechanical vibratory system can be set into vibration by a driving force

impendance

the extent to which the system resists the flow of energy through it

admittance

the ease at which energy will flow through the vibrating system

when does peak admittance occur?

when air pressure is equal on both sides - in the ear canal and in the middle ear space

factors affecting immittance in the middle ear system

-mass: as mass increases, impedance increases/ admittance decreases, which may reduce the flow of energy through the middle ear system

-stiffness: as stiffness increases, impedance increases/ admittance decreases, which may reduce the flow of energy throughout the middle ear system

acoustic reflex

stapedius muscle contracts reflexively and bilaterally in response to an intense sound presented to either ear; causes tympanic membrane to stiffen and decrease in admittance

otoacoustic emissions (OAEs)

very low level acoustic energy (-10 to 20 dB SPL) produced by the cochlea, with the primary sound coming from the active process of the outer hair cells; can provide information about the functional status of the cochlear-active process; travel back out through the middle ear and vibrate the tympanic membrane

auditory brainstem response (ABR)

neuroelectric responses from the 8th cranial nerve and brainstem pathways in response to brief sounds, measured with electrodes on the surface of the head

Distortion Product Otoacoustic Emissions (DPOAEs)

must be 6 dB SNR above noise floor to be considered present/ normal

What does the presence of OAEs suggest about the condition/disorders?

suggests good OHC function as well as normal middle and outer ear status

What does the absence of OAEs suggest about the condition/disorders?

can occur with any degree of cochlear hearing loss and involving OHC or a problem in the conductive parts of the ear

normal ABR waveform

waveform should be clear and present, with wave V being the largest and most used clinically; look for regularly reoccurring waves and amplitude

How does ABR change with intensity?

are reduced and delayed with decrease in intensity and eventually reduce to noise level; determine lowest intensity level to evoke a repeatable wave V