What is masking?
The ability of one acoustic signal to obscure the presence of another acoustic signal so it cannot be detected
Keeping one ear busy so that we can get accurate results for the ear being tested
What does masking do?
Raises the threshold of audibility for one sound by the presence of another (masking)
What is the test ear?
Ear that the signal is directed to
What is the non test ear?
Ear receiving masking noise
Why is masking needed?
What is crossover?
What is inter-aural attenuation?
True or false: type of transducer used affects interaural attenuation
True
What is the lowest acceptable interaural attenuation for supra-aural headphones? Insert earphones?
40 dB supra aural
70 dB insert earphones
Anytime the _ conduction threshold in one ear differs from the _ or _ conduction threshold in the other ear by _ or _ dB, crossover may have occurred and the _ ear will need to be isolated acoustically
air
air, bone
40, 70
better
What is the interaural attenuation for bone conduction?
0 dB
Placing bone vibrator on the mastoid, assume that the tone may be heard in both ears
With bone oscillator testing, we can assume that the patient hears the tone in the ear with the better __
Cochlea
We will always mask bone conduction testing if there is an air bone gap of ____ dB HL or more
15
Why do we use masking?
How is masking performed for pure tones?
How is masking performed for speech audiometry?
What is the first step when determining if masking is needed?
Confirm if crossover occured
Procedure for confirming cross over
After crossover has been confirmed, what procedure is followed to find the true threshold of the test ear?
What is the plateu?
Levels between undermasking and overmasking at which true threshold of the test ear is established
What is undermasking?
What is overmasking?
On the audiogram, symbols are ___ to indicate that masking was used
- level of masking is also sometimes indicated
What is the minimum masking level?
- usually 10 dB above air conduction threshold in non test ear