Help with masking homework

[SarahCMU]

We just learned about masking in our Diagnostic Audiology class. I am looking at the audiogram we have to analyze and I was wondering what the minimum effective masking level was. If the bad ear's threshold was 30 dB HL let's say, would the effective masking level be 30 dB EM?

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[rEliseMe]

I have quoted from this book.

"Starting level for masking is set at an intensity slightly above the minimum necessary masking. As a safety factor, 10- to 15-dB is added to the minimum necessary masking to account for the normal threshold sensitivity variability. By adding the 10- to 15-dB safety factor, one ensures that the masking signal is at an effective level just above the threshold of the masked ear. During testing, the factors needed to calculate the starting level for pure tone A/C testing are the threshold of the NTE (the masked ear) and the safety factor of 10- to 15-dB."

Basically, add 15 to the threshold of the masked ear. If you are masking their left ear and the threshold in that ear is 30dB, then your "effective masking level" would be ~45dB. That's what I gather, anyway.

 

[SufjanS]

I am pretty sure this depends on whether or not we are talking about bone conduction or air conduction testing

 

[BigAl]

NTE threshold+ occlusion effect + safety factor=EM for BC

 

[rEliseMe]

NTE threshold+ occlusion effect + safety factor=EM for BC

Right, good point re: occlusion effect. Supra-aural headphones will have a different occlusion effect than insert phones.