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110 Effects of Whole Body Vibration on Hearing Level Shifts
  1. S A M N Moussavi-Najarkola1,
  2. Khavanin2,
  3. Mirzaei3,
  4. Salehnia4
  1. 1College of Health, Shahid Beheshti University of Medical Sciences (SBUMS), Tehran, Iran
  2. 2Department of Occupational Health, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
  3. 3Department of Occup. Health, Faculty of Health, Zahedan University of Medical Science, Zahedan, Iran
  4. 4Department of Anatomical Sciences, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran

Abstract

Background and Aim Adverse effects of occupational whole body vibration (WBV) on hearing are yet unknown. The aim of the research was to survey effects of whole body vibration on hearing shifts.

Methods Male adult New Zealand White rabbits were divided into two groups include control group (n = 6, not exposed to whole body vibration) and vibration group (n = 6, exposed to whole body vibration in the Z-axis at 4 Hz and 1.0 ms-2 r.m.s for 8 hours per day in 5 consecutive days by putting their box on a vibrating platform). DPOAEs were measured hearing shifts in vibration group in days: zero (before exposure to vibration) as baseline, eighth (an hour after exposure to vibration) as temporary threshold shifts, and tenth (48 hours after exposure to vibration) as permanent threshold shifts. Similarly, DPOAEs were also examined hearing shifts in control group in days zero, eighth, tenth. The gathered data analysed by independent-samples T Test.

Results Increased mean DPOAEs amplitudes were observed in frequencies 375.00, 562.50, 750.00, 1125.00, 1312.50, 2062.50, 2625.00, 3937.50, 5437.50, 6562.50 Hz respectively in vibration group. There were no any significant differences between mean DPOAEs amplitudes in days zero, eighth and tenth at all frequencies (p = 0.073).

Conclusion The exposure to vibration significantly led to enhanced mean DPOAEs amplitudes at all frequencies at low frequencies rather than at high frequencies. Thus, this study showed that vibration exposure only could not cause temporary or permanent threshold shifts. Increased DPOAEs amplitudes could be probably attributed to normal outer and destroyed inner hair cells.

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