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Effects of Infrasound Exposure on Measures of Endolymphatic Hydrops

NCT03132961 · Status: TERMINATED · Type: OBSERVATIONAL · Enrollment: 12

Last updated 2018-10-18

No results posted yet for this study

Summary

Persons exposed to infrasound - frequencies below 20 Hz - describe a variety of troubling audiovestibular symptoms, but the underlying mechanisms are not understood. Recent animal studies, however, provide evidence that short-term exposure to low frequency sound induces transient endolymphatic hydrops. The existence of this effect has not been studied in humans. The long-term objective of this research is to identify a possible mechanism to describe the effects of infrasound on the human inner ear. The central hypothesis of the proposed study is that short-term infrasound exposure induces transient endolymphatic hydrops in humans. This will be tested by performing electrophysiologic tests indicative of endolymphatic hydrops among normal hearing individuals before and immediately after a period of infrasound exposure. Recordings of infrasound generated by wind turbines in the field have been established and calibrated by this team of engineers, otologist, and hearing and balance scientists. An infrasound generator reproduces the acoustic signature based on these field recordings. Aim 1: Determine the effect of infrasound on the summating potential to action potential (SP/AP) ratio on electrocochleography (ECoG). Hypothesis 1: Infrasound exposure will cause a reversible elevation of the SP/AP ratio. Aim 2: Determine the effect of infrasound on the threshold response curves of ocular and cervical vestibular evoked myogenic potentials. (oVEMP and cVEMP). Hypothesis 2: Infrasound exposure will cause elevation of the oVEMP and cVEMP thresholds at the frequency of best response. Successful completion of the aims will provide evidence for a possible mechanism of the effect of infrasound on the inner ear. This understanding will benefit individuals exposed to environmental infrasound and those in regulatory, research, and advocacy roles when crafting interventions and future policy.

Conditions

  • Vestibular Abnormality
  • Endolymphatic Hydrops

Interventions

OTHER

Infrasound exposure

All cohorts will receive an identical infrasound exposure of equal time duration, varying only the order in which the testing is performed. To simulate the frequencies generated by a common source of environmental infrasound (wind turbines), recordings measured at a full-scale research wind turbine at the University of Minnesota will be utilized to create an infrasound stimulus. The resultant sound file consists of the fundamental frequency at approximately 0.7 Hz, equal to the blade passage rate, plus the harmonic overtones of the fundamental frequency. The presentation level is 85 dB SPL. The stimulus will be presented in a sound field.

Sponsors & Collaborators

Principal Investigators

  • Meredith E Adams, MD · Assistant Professor

Eligibility

Min Age
18 Years
Max Age
60 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2018-05-05
Primary Completion
2018-08-23
Completion
2018-08-23

Countries

  • United States

Study Locations

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Entities

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT03132961 on ClinicalTrials.gov