Distribution characteristics of normal pure-tone thresholds
Robert H Margolis1, Richard H Wilson2, Gerald R Popelka3
1a Audiology Incorporated, Arden Hills , Minnesota , USA.
International Journal of Audiology
|May 5, 2015
Summary
Automated audiometry yields normal hearing threshold distributions, unlike manual testing which shows higher thresholds and skew, potentially due to "Good enough bias" in audiologists.
Area of Science:
- Audiology
- Hearing Science
- Biostatistics
Background:
- Normal hearing thresholds are typically assumed to follow a normal distribution.
- Automated and manual audiometry methods may yield different threshold distributions.
- Investigating these differences can reveal potential biases in testing procedures.
Purpose of the Study:
- To statistically analyze normal air-conduction hearing thresholds from automated and manual audiometry.
- To test the hypothesis of normally distributed thresholds.
- To identify potential biases in manual audiometry.
Main Methods:
- Analysis of 317,569 threshold determinations from 80,547 subjects across four clinical databases.
- Examination of frequency distributions for thresholds at 250, 500, 1000, and 2000 Hz.
- Comparison of data from one automated audiometry database and three manual audiometry databases.
Main Results:
- Automated audiometry produced normally distributed hearing thresholds.
- Manual audiometry data showed distributions shifted towards higher thresholds.
- Two of three manual datasets exhibited positive skew, indicating a bias.
Conclusions:
- The observed shift and skew in manual audiometry data suggest potential tester bias.
- A phenomenon termed "Good enough bias" may explain why audiologists identify fewer low thresholds.
- This bias could account for the discrepancies between automated and manual audiometry threshold distributions.
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