audio exam 2 Flashcards
scale of hearing impairment for adults (children)
normal -10 to (15) 25 mild (16) 26 to 40 moderate 41 to 55 mod-sev 56 to 70 severe 71 to 90 profound >91
audiometry purpose
Determine the degree of hearing loss
Estimate the location of the lesion within the auditory system
Help establish the cause of the hearing problem
Estimate the extent of the handicap produced by the hearing loss
Help to determine the client’s (re)habilitative needs and the appropriate means of filling those needs
pure tone aud
sensitivity thresholds (heard 50%) are obtained for each ear for pure tone stimuli of different frequencies 250, 500, 1000, 2000, 4000 & 8000 Hz
audiogram symbols
s= sound field; f= free field right red air unmasked: 0 masked: triangle bone unmasked: < masked: [ left blue air unmasked: X masked: square bone unmasked: > masked: ]
threshold procedure
Begin testing at 30 dB, 1000 Hz
If no response, Increase to 50 dB
Continue increasing in 10 dB steps until patient responds
If patient does not respond at output limits of audiometer repeat presentation at output limits 3x and record no response
If patient does responds, down in 10 dB steps until patient no longer responds
When patient does not respond increase intensity in 5 dB steps
down 10 up 5
Modified Hughson-Westlake Procedure
Correct response – lower by 10 dB
Incorrect response – raise by 5 dB
Ascending approach avoids an error in anticipation
Patient who responds to several tones of decreasing intensity is likely to continue to respond
Patient in a “rhythm”
Descending approach yields threshold values that are slightly lower than those of ascending approach
tone duration
Signal duration should be 1 to 2 sec
Pulsed tones somewhat more helpful than continuous tone
200 ms on and 200 ms off
Uses advantage of on-effect
Improved audibility is caused by the increased neural activity at the beginning of the signal
Also aids in those with tinnitus
threshold frequencies
250 500 1k 2k 4k 8k
ambient noise levels
500 --22 1000 -30 2000 - 34 4000- 42 8000-45
air conduction procedure
Begin at 1000 Hz – easily heard by most and high test-retest reliability
ORDER of FREQS: 1000, 2000, 4000, 8000,
recheck of 1000, 500, then 250
Test at the octave points and the mid-octaves (750, 1500, 3000, 6000 Hz) if there is a difference of 20 dB or more between adjacent octaves
why 1000?
One of the mid-range frequencies to which the human ear is more sensitive to than lower or higher frequencies
Has a pitch that is more familiar to most listeners
Less affected by background noise and physiological noise than low frequencies
The wavelength in relation to the length of the ear canal makes test-retest reliability better than higher frequencies
Test-retest reliability: measure of the consistency of test results from one trial to the next
pure tone average
PTA is calculated as the mean/average of the threshold levels at 500 Hz, 1000 Hz and 2000 Hz
Useful for predicting the threshold for speech
To establish the degree of communication impact imposed by a hearing loss
bone conduction
bone– move cochlear fluid– hair cells
Inertial stimulation- stored energy moving fluid
Osseotympanic stimulation- proximal stimulation TM-negiligible
Hearing by bone conduction results from an interaction of these three ways of stimulating the inner ear
occlusion effect
Artificial enhancement of bone conduction hearing as a result of the ears being covered
Effects bone conduction thresholds at
250 Hz – 30 dB
500 Hz – 20 dB
1000 Hz – 10 dB
OE is the result of the increase of sound pressure level in the external auditory canal when the ear is covered
interaural attenuation
Loss of energy of a sound (either by air or bone conduction) as the sound crosses from the test to the nontest ear
0 dB for bone conducted stimulus
40 dB for supra-aural earphones
50 dB for insert earphones
