Time-frequency analyses of transient-evoked stimulus-frequency and distortion-product otoacoustic emissions: Testing cochlear model predictions

Purpose: To present a case study in order to alert clinicians to the possibility of occurrence of intermodulation distortion during otoacoustic emissions testing that arises from the cavity formed by the external auditory meatus and tympanic membrane rather than from the inner ear, compromising the reliability and validity of otoacoustic emissions testing. Research Design: Prospective case study. Study Sample: A young (26-year-old) female adult with a longstanding, bilateral, essentially moderate to severe sensorineural hearing loss presented with robust distortion product otoacoustic emissions. Results: Repeat otoacoustic emissions testing with another device of the same model revealed essentially absent distortion product otoacoustic emissions and transient otoacoustic emissions. Calibration of both otoacoustic emissions devices using a 1 cc membranous cavity indicated present intermodulation distortion for the device that yielded robust distortion product otoacoustic emissions for the patient but absent intermodulation distortion for the device that revealed absent distortion product otoacoustic emissions and absent transient evoked otoacoustic emissions for the patient. The calibration findings for the device yielding intermodulation distortion in the cavity were confirmed by an engineer of a technical instrumentation company. The device was shipped back to the manufacturer of the device for repair. The manufacturer's engineers diagnosed the problem as an interruption in the relay system. Following repair, calibration revealed the absence of intermodulation distortion in the 1 cc membranous cavity. Conclusions: The findings have implications for the reliability and validity of otoacoustic emissions. Clinicians should routinely calibrate otoacoustic emissions devices using 1.0 and 0.5 cc membranous cavities to rule out intermodulation distortion that could produce artifactual otoacoustic emissions in patients.

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Individual Differences and the Reliability of 2F1-F2 Distortion-Product Otoacoustic Emissions

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3906.1138 ◽

1996 ◽

Vol 39 (6) ◽

pp. 1138-1148 ◽

Cited By ~ 35

Author(s):

Anthony T. Cacace ◽

William A. McClelland ◽

Jordan Weiner ◽

Dennis J. McFarland

Keyword(s):

Pulse Rate ◽

Otoacoustic Emissions ◽

Stimulus Frequency ◽

Gender Effects ◽

Distortion Product Otoacoustic Emissions ◽

Oral Temperature ◽

Distortion Product ◽

Time Period ◽

And Gender ◽

Subject Differences

Distortion product otoacoustic emissions (DPOAEs) measured from the ear canal can be a sensitive tool to detect changes in cochlear function over time. However, if multiplemeasurement procedures are to be useful clinically, testing needs to be reliable and sources of variability within individuals should be known. Herein, the influence of time-of-day (TOD), stimulus frequency, stimulus sound pressure level (SPL), and gender were evaluated on 2f1-f2 DPOAE amplitude in 16 adult volunteers with normal hearing. The effects of oral temperature and resting-pulse rate were also assessed. This study demonstrated a TOD main effect, with a period approximating one cycle-per-day. The magnitude of this effect averaged less than one dB and was not dependent on stimulus (frequency or SPL) or participant variables (gender, oral temperature, or resting-pulse rate), nor was it synchronized to a particular point-in-time. Stimulus level and gender effects on DPOAEs across frequency were also observed. Using generalizability theory (GT), DP iso-level/frequency profiles (DPILFPs) were found to be reliable measures within-subjects over a contiguous 24-hour time period. Significant and reliable between-subject differences were also documented. This study demonstrates the influence of stimulus and participant variables, quantifies the within-subject reliability over a 24-hour time period, and confirms that significant and reliable between-subject differences exist on DPOAEs across frequency, SPL, and gender.

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