MOCR on HearID

CAS add-on

Also available for the TE and SF Modules for research users is a contralateral elicitor add-on (MOCR module customers get this add-on for free). The add-on generates digital broad-band noise or a tone, synchronizes the output with the SFOAE measurement (including programmable on and offset delays), and automatically saves the data files with a common file prefix. The benefit to using the add-on is that test sequences can be highly customized, but there is no real-time display of the MOCR results or any data analysis. This add-on is software only - a suitable sound card and calibrated earphone must be purchased or acquired separately.

Resources

Manuals

• MOCR user manual (pdf).

Further Reading

A Clinically Viable Medial Olivocochlear Reflex Assay Using Transient-Evoked Otoacoustic Emissions. by Lapsley Miller, J. A., Reed, C. M., Marshall, L., Perez, Z. D., and Villabona, T. (2023). Ear Hear., Online Ahead of Print.

• Show/Hide Abstract... 
  OBJECTIVES: The contralateral medial olivocochlear reflex (MOCR) strength may indicate various auditory conditions in humans, but a clinically viable assay and equipment are needed for quick, accurate, and reliable measurements. The first experiment compared an earlier version of the assay, which used a nonlinear-mode chirp stimulus, with a new assay using a linear-mode click stimulus, designed to give reliable MOCR measurements in most normal-hearing ears. The second experiment extended the improved assay on a purpose-built binaural hardware platform that used forward-pressure level (FPL) calibration for both the stimulus and the contralateral MOCR elicitor. DESIGN: Transient-evoked otoacoustic emission (TEOAE) tests were measured with and without a 60-dB SPL MOCR-evoking contralateral broadband noise. The normalized MOCR strength (MOCR%) was derived from the TEOAE responses for each trial pair using the complex pressure difference weighted by the TEOAE magnitude. Experiment 1 compared MOCR% within-subject and across-day using two TEOAE stimuli: nonlinear-mode chirps (50 dB SPL, bandpass 1-5 kHz, 14 ms window delayed by 2 ms) and linear-mode clicks (50 dB SPL, bandpass 0.5-2.5 kHz, 13 ms window delayed by 5 ms). TEOAE responses were analyzed in the 0.5 to 2.5 kHz band. Thirty adult participants with normal hearing (30 ears) completed the study. The TEOAE stimulus was calibrated in situ using spectral flattening, and the contralateral noise was calibrated in a coupler. Twelve TEOAE trial pairs were collected for each participant and condition. Experiment 2 used a purpose-built binaural system. The TEOAE stimuli were linear-mode clicks (50 dB SPL, bandpass 1-3 kHz, 13 ms window delayed by 5 ms), analyzed in the 1 to 3 kHz band over ~12 trial pairs. After a probe refit, an additional trial pair was collected for the two early-stopping signal-to-noise ratio criteria (15 and 20 dB). They were evaluated for single-trial reliability and test time. Nineteen adult participants with normal hearing (38 ears) completed the study. The TEOAE clicks and contralateral elicitor noise were calibrated in situ using FPL and delivered with automated timing. RESULTS: MOCR% for linear-mode clicks was distinguishable from measurement variability in 98% to 100% of participants' ears (both experiments), compared with only 73% for the nonlinear-mode chirp (experiment 1). MOCR detectability was assessed using the MOCR% across-subject/within-subject variance ratio. The ratio in experiment 1 for linear-mode clicks was higher (8.0) than for nonlinear-mode chirps (6.4). The ratio for linear-mode clicks (8.9) in experiment 2 was slightly higher than for the comparable linear-mode stimulus (8.0) in experiment 1. TEOAEs showed excellent reliability with high signal-to-noise ratios in both experiments, but reliability was higher for linear-mode clicks than nonlinear-mode chirps. MOCR reliability for the two stimuli was comparable. The FPL pressure response retest reliability derived from the SPL at the microphone was higher than the SPL retest reliability across 0.4 to 8 kHz. Stable results required 2 to 3 trial pairs for the linear-mode click (experiments 1 and 2) and three for the nonlinear-mode chirp (experiment 1), taking around 2 min on average. CONCLUSIONS: The linear-mode click assay produced measurable, reliable, and stable TEOAE and MOCR results on both hardware platforms in around 2 min per ear. The stimulus design and response window ensured that any stimulus artifact in linear mode was unlikely to confound the results. The refined assay is ready to produce high-quality data quickly for clinical and field studies to develop population norms, recognize diagnostic patterns, and determine risk profiles.
• Access via PubMed

Marshall, L., Lapsley Miller, J. A., Guinan, J. J., Shera, C. A., Reed, C. M., Perez, Z. D., Delhorne, L. A., and Boege, P. (2014). "Otoacoustic-emission-based medial-olivocochlear reflex assays for humans," J. Acoust. Soc. Am. 136, 2697-2713.

Lapsley Miller, J. A., Marshall, L., Reed, C. M., Perez, Z. D., and Villabona, T. (2021). Refining the procedures for medial-olivocochlear reflex (MOCR) assays: decreasing the contralateral noise reset time below 10 seconds can affect subsequent transient-evoked otoacoustic emission (TEOAE) measurements (NSMRL Technical Report No. 1344). Groton, CT: Naval Submarine Medical Research Laboratory.

Lapsley Miller, J. A., Marshall, L., Reed, C. M., and Villabona, T. (2021). Effects of stopping rules, stimulus levels, and ear laterality on transient-evoked otoacoustic emission (TEOAE)-based assays of the medial-olivocochlear reflex (MOCR) (NSMRL Technical Report No. 1346). Groton, CT: Naval Submarine Medical Research Laboratory.

Lapsley Miller, J. A., Marshall, L., Reed, C. M., and Perez, Z. D. (2021). Otoacoustic Emission (OAE) Based Assays of the Medial Olivocochlear Reflex (MOCR): Ensuring the OAE Stimulus Does Not Cause a Confounding MOCR (NSMRL Technical Report No. 1345). Groton, CT: Naval Submarine Medical Research Laboratory.