Modules
Pure-tone audiometry

Pure-tone audiometry

The PTA module is currently research-only and only available for the binaural OtoStat with an external push button. The automated pure-tone audiometry (PTA) module implements an automated algorithm based on the modified Hughson-Westlake (MHW) method. It meets the criteria for an ANSI Type 4 audiometer (ANSI, 2010).

In addition, it provides the ability to test with forward-pressure level calibration. This method was shown to vastly increase test-retest reliability. RETSPL/audiometric zero has yet to be established for the ER10C probe using forward-pressure level calibration – the included dB HL (FPL) should only be considered indicative at this stage.

The PTA module also provides real-time noise detection and retesting on a no-response. The criteria for these thresholds are yet to be validated, but are user-editable. PTA testing can also be run in Screening mode. PTA tests can be chained, so in the presence of too much noise, the MHW procedure can automatically detect and switch to Screening mode to allow a determination of normal/abnormal/fitness-for-duty status even if hearing thresholds cannot be established.

Developed in collaboration with the US Navy, this module is currently research-only.

Tracking STS

Significant threshold shifts are shown by flagging a test as a baseline. Follow-up tests then show significant changes relative to this baseline. These results are reported in the audiogram plot and numerically.

PTA on OtoStat

To run OtoStat+PTA, you need a binaural OtoStat with the PTA Measurement Module and push button.

• Type IV screener, testing up to 70 dB HL and from 250 to 8000 Hz.
• Preset measurement protocols included.
• Save your favorite protocols by name.
• Automated audiometry with noise detection.
• Create test batteries with our test sequencer. Run PTA, MEPA, OAE, and other tests all with the same probe fit and little-to-no intervention needed from the tester.
• Multiple views during real time data collection and in data review.
• In-the-ear probe calibration, using standard or forward-pressure level calibration.
• Detailed results export provides extensive data for offline analysis.

Resources

• OtoStat User Manual (pdf)
• Pure-Tone Audiometry With Forward Pressure Level Calibration Leads to Clinically-Relevant Improvements in Test-Retest Reliability. by Lapsley Miller, J. A., Reed, C. M., Robinson, S. R., and Perez, Z. D. (2018). Ear Hear., 39(5), 946-957.
  • Show/Hide Abstract...
    OBJECTIVES: Clinical pure-tone audiometry is conducted using stimuli delivered through supra-aural headphones or insert earphones. The stimuli are calibrated in an acoustic (average ear) coupler. Deviations in individual-ear acoustics from the coupler acoustics affect test validity, and variations in probe insertion and headphone placement affect both test validity and test-retest reliability. Using an insert earphone designed for otoacoustic emission testing, which contains a microphone and loudspeaker, an individualized in-the-ear calibration can be calculated from the ear-canal sound pressure measured at the microphone. However, the total sound pressure level (SPL) measured at the microphone may be affected by standing-wave nulls at higher frequencies, producing errors in stimulus level of up to 20 dB. An alternative is to calibrate using the forward pressure level (FPL) component, which is derived from the total SPL using a wideband acoustic immittance measurement, and represents the pressure wave incident on the eardrum. The objective of this study is to establish test-retest reliability for FPL calibration of pure-tone audiometry stimuli, compared with in-the-ear and coupler sound pressure calibrations. DESIGN: The authors compared standard audiometry using a modern clinical audiometer with TDH-39P supra-aural headphones calibrated in a coupler to a prototype audiometer with an ER10C earphone calibrated three ways: (1) in-the-ear using the total SPL at the microphone, (2) in-the-ear using the FPL at the microphone, and (3) in a coupler (all three are derived from the same measurement). The test procedure was similar to that commonly used in hearing-conservation programs, using pulsed-tone test frequencies at 0.5, 1, 2, 3, 4, 6, and 8 kHz, and an automated modified Hughson-Westlake audiometric procedure. Fifteen adult human participants with normal to mildly-impaired hearing were selected, and one ear from each was tested. Participants completed 10 audiograms on each system, with test-order randomly varied and with headphones and earphones refitted by the tester between tests. RESULTS: Fourteen of 15 ears had standing-wave nulls present between 4 and 8 kHz. The mean intrasubject SD at 6 and 8 kHz was lowest for the FPL calibration, and was comparable with the low-frequency reliability across calibration methods. This decrease in variability translates to statistically-derived significant threshold shift criteria indicating that 15 dB shifts in hearing can be reliably detected at 6 and 8 kHz using FPL-calibrated ER10C earphones, compared with 20 to 25 dB shifts using standard TDH-39P headphones with a coupler calibration. CONCLUSIONS: These results indicate that reliability is better with insert earphones, especially with in-the-ear FPL calibration, compared with a standard clinical audiometer with supra-aural headphones. However, in-the-ear SPL calibration should not be used due to its sensitivity to standing waves. The improvement in reliability is clinically meaningful, potentially allowing hearing-conservation programs to more confidently determine significant threshold shifts at 6 kHz-a key frequency for the early detection of noise-induced hearing loss.
  • Access on publisher's website