1 - Masking Flashcards
When is masking necessary?
During air conduction: when we cannot be sure that we are actually testing the ear we think we are testing due to the cross over effect
During bone conduction: when we are not sure if the problem is with the outer and/or middle ears or that of the cochlea and/or nervous system
What is masking?
Masking is a process where the threshold of audibility is raised by the presence of a second sound
What is Interaural Attenuation?
A decrease in a signal’s intensity as it passes from one ear to the other
Interaural Attenuation values will vary due to __________ and the __________.
Frequency of the signal
Transducer being used (Bone, insert earphones, etc.)
When using bone conduction, the signal reaching the cochlea _________.
Is approximate the same in both ears
Without masking, a bone conduction signal may be heard by ________.
The right, the left, or both ears
When unmasked, bone conduction thresholds are determined by _________.
The better ear
How does the signal cross the head during air conduction?
Via bone conduction
When do you need to mask during air conduction?
When there is a 40 dB difference between the threshold of the right ear versus that of the left
If one or both ears hears in a normal range then ___________.
We assume that the bone conduction levels will match that ear
What is the lowest interaural attentuation at which crossover might occur?
40 dB
Is masking ever used during speech audiometry testing?
Yes
Why are insert headphones preferred by audiologist?
Masking Version
They provide for a larger interaural attenuation value
This means less masking dilemmas
What is a shadow curve?
When the hearing threshold curve of a poor to nonfunctioning ear mirrors that of the better ear
This usually means that the better ear is hearing the signal and making the poorer ear seem better than it actually is
When you see a shadow curve, you need _____.
To mask
What sort of noise is usually used for masking?
Narrowband Noises
What is white noise?
A random and equal representation of all frequencies of equal intensity
What is narrowband noise?
Filtered white noise where the center frequency is the test signal
What is speech weighted noise?
Similar to white noise but shaped to mirror the frequency spectrum of speech
During a hearing test, what do we call it when a sound is intense enough to be relayed to the opposite ear via bone conduction?
Cross Over Effect
When does the cross over effect occur most often?
During bone conduction
The cross over effect makes it hard to test _____ and _____.
Hearing sensitivity
Sensorineural sensitivity
What sorts of noises can be used for masking?
3
White Noise
Narrowband Noise
Speech Weighted Noise
What does white noise sound like?
Static
When is speech weighted noised used when masking?
During speech audiometry
When does interaural attenuation occur?
When sound that is transmitted by either air or bone conduction to the test ear that arrives at the opposite ear via bone conduction
What is attenuation?
A decrease in intensity
What is a masked threshold?
The threshold of audibility for a specific sound in the presence of another sound (masker)
What is a masker?
An sound whose prescence raises the threshold of audibility of another sound
When there is a difference between bone conduction and air conduction of ________, masking is necessary
10 dB in the same ear
When there is a difference in air conduction levels between the right and left ears of ________, masking is necessary.
40 dB between the two ears
The masking level used in clinical audiometry should never be _____ than the ______ of _______.
Less
Air conduction threshold
The ear being masked
What is the minimum masking level?
When the masker is at a level just sufficient enough to mask the test signal
What is the maximum masking level?
The highest level a masker can be introduced into the non-test ear without over masking
What is overmasking?
When the masker crosses into the test ear making the test ear’s threshold poorer
If the Bone Conduction Level is _____ than the Air Conduction Level in ______ then you will need to use masking to find the threshold for ______ in that ear.
10 dB better
The same ear
Bone conduction
If the Air Conduction Level in one ear is _____ than ______ then you will need to use masking to find the threshold for ______ in ______ ear.
40 dB
The Air Conduction Level in the opposite ear
Air Conduction
The poorer
Which ear is masked?
The non-test ear
The test ear can also be masked but this is not usually done in clinical situations
