Short-term variability of pure-tone thresholds obtained with TDH-39P earphones

Abstract

Objective: To estimate the short-term variability and correlates of variability in pure-tone thresholds obtained using audiometric equipment designed for occupational use, and to examine the justification for excluding 8 kHz as a mandatory threshold in occupational hearing conservation programs. Method: Pure-tone thresholds and other hearing-related tests (e.g. noise dosimetry, otoscopy, middle-ear assessment) were conducted with a group of 527 adults between 20 and 69 years of age. Five measurement visits were completed by participants within 14 days. Results: The 50% critical difference boundaries were − 5 and 0 dB at 4 kHz and below and − 5 and 5 dB at 6 and 8 kHz. The likelihood of spurious notches due to test-retest variability was substantially lower than the likelihood of failing to detect a notched configuration when present. Correlates of variability included stimulus frequency, baseline threshold, acoustic reflectance of the ear, average noise exposure during the previous eight hours, age, and the tester's level of education in audiology. Conclusion: The short-term variability in 8-kHz pure-tone thresholds obtained with the TDH-39P earphone was slightly greater than at other frequencies, but this difference was not large enough to justify the disadvantages stemming from the inability to detect a 6-kHz notch.

Key Words::

• Audiometry
• noise-induced hearing loss
• reliability
• occupational health

Acknowledgements

The authors thank William J. Murphy, Peter B. Shaw (CDC/NIOSH/Division of Applied Research and Technology), Elliott Berger (3M Personal Safety Division, Indianapolis, USA), Jack Foreman (Tremetrics, Eden Prairie, USA), Kim Schairer (VAMC-Mountain Home, USA), John Brown, Chas Pudrith, Lydia Baldwin, Emma Trabue, Joyce Gard, and Hannah Borton (WMU) for their assistance with this project.

Declaration of interest: The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

This study was supported by CDC/NIOSH Contract 211-2009-31218. Preliminary findings from this study were presented at the 2013 National Hearing Conservation Annual Conference in St. Petersburg, USA.