24564693

PMC4668587

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. A total of five measurement visits were completed by participants within a 14-day period.

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 8 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.

CDC Public Access

CC999999/Intramural CDC HHS/United States