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What if cross-hearing is a problem?

Learn about cross-hearing challenges and essential masking procedures to prevent Non-Test Ear (NTE) responsiveness. Explore central vs. peripheral masking, types of maskers, and methods for optimal masking levels. Discover the risks of overmasking and undermasking in audiometric testing.

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What if cross-hearing is a problem?

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  1. What if cross-hearing is a problem? • Necessary to prevent NTE from responding. • Procedure: MASKING. • Types of masking: Central versus peripheral • Central masking: Elevation of threshold of a pure tone presented to one ear when noise is presented to the other ear. Around 5 dB threshold shift. • What types of maskers? Noise (white versus narrow).

  2. Effective masking (EM) • Amount of threshold shift provided by a certain amount of noise. • 20 dB EM is the amount of noise just enough to make a 20 dB HL 1000 Hz tone inaudible. • A 25 dB HL tone would be audible in the presence of 20 dB EM noise.

  3. Methods for masking • ‘Shotgun’ method • Minimum noise method: Use effective masking level in the non-test ear. Just enough noise to shift AC and BC thresholds in the non-test ear by 5 dB. • Maximum masking: BCTE + IA – 5 • Danger of overmasking, where masking level exceeds BCTE + IA – 5

  4. Hood’s plateau method • Measure unmasked threshold in test ear. • Present noise to non-test ear, starting at effective masking level. • Present tone. Test-ear threshold will probably go up. WHY? • If the tone is heard, then increase masking noise level in 5 dB steps till tone is not heard. • If the tone is not heard, then increase tone level till it becomes audible again. • At some point, tone will be heard even after masking noise level has increased several steps: PLATEAU • This is the masked threshold of the test ear.

  5. Minimum masking Maximum masking Sufficient masking Overmasking Undermasking

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