SF: Stimulus-Frequency Otoacoustic Emission (SFOAE) Module
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| HearID+SF screenshot, showing an example SFOAE test in an ear with low-level OAEs. Stimulus and calibration levels are on the left. The SFOAE-gram is at the top right. The SFOAE phase is at the bottom right. In this example, low-level SFOAEs are validated because their phase rapidly changes with frequency - a marker for a reflection-component OAE. |
SFOAE testing is available to our research clients in the SF Module for HearID. It implements the Shera & Guinan (1999) test protocol.
Test protocols are flexible and customizable. Test frequencies can be evenly spaced in linear, log, or power-law spacing, and/or clustered at key frequencies. Clustering allows SFOAE group delay to be estimated efficiently without measuring the entire spectrum.
Out of all the OAE measurement types, SFOAEs provide the most direct and clear measurement of the reflection-component OAE, which is thought to be most vulnerable to cochlear insult (Shera, 2004).
Also available for SF Module research users is a contralateral elicitor add-on. 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. This add-on is software only - a suitable sound card and calibrated earphone must be provided.
Further Reading
Shera, C. A., and Guinan, J. J. (1999). Evoked otoacoustic emissions arise by two fundamentally different mechanisms: a taxonomy for mammalian OAEs, Journal of the Acoustical Society of America 105, 782-798.
Shera, C. A. (2004). Mechanisms of Mammalian Otoacoustic Emission and their Implications for the Clinical Utility of Otoacoustic Emissions, Ear Hear, 25, 86-97.
Lapsley Miller, J. A., Boege, P., Marshall, L., Shera, C., & Jeng, P. S. (2004). Stimulus-frequency otoacoustic emissions: Validity and reliability of SFOAEs implemented on Mimosa Acoustics SFOAE measurement system v2.1.18. (Technical Report No. 1231). Groton, CT.: Naval Submarine Medical Research Laboratory. (Download Full Document in PDF format)
