Cochlear distribution of small focal lesions following exposure to a 4-kHz or a 0.5-kHz OBN

Details

• Personal Author:
  Bohne BA ; Harding GW
• Description:
  An octave band of noise (OBN) delivers fairly uniform energy over a specific range of frequencies (3-6 kHz for 4-kHz OBN & 0.375-0.750 kHz for 0.5-kHz OBN). Above & below these ranges, energy is at least 50 dB less than that in the OBN. Hair-cell loss often occurs outside the exposure OBN. The frequency location of hair-cell loss is evident when the % location of small focal lesions is analyzed. Data sets were assembled from our permanent collection of noise-exposed chinchillas using the following criteria: 1) The sum of exposure duration & recovery time was less than or equal to 10 days; 2) The exposure level was less than or equal to 108 dB SPL; & 3) Focal lesions were less than 1.5 mm in size. The data sets included a variety of exposures ranging from those that were high-level, short duration to those that were moderate-level, moderate duration. The % location of the center of each focal lesion was determined. Means, SDs & medians were calculated for lesion size for each OBN. Histograms were then constructed from the % location data using 2.0% bins & the counts were graphed relative to total number of lesions. For the 4-kHz OBN, 94% of the lesions were in the basal half of the OC & 6% were in the apical half. For the 0.5-kHz OBN, 29% of the lesions were in the apical half of the OC & 71% were in the basal half. The mean lesion size was 1.48% & 0.68% for the 4-kHz & 0.5-kHz OBN, respectively, with medians of 1.10% & 0.50%. The mean lesion size (in mm) for the 0.5-kHz OBN was less than half that for the 4-kHz OBN. For the 4-kHz OBN, a histogram of the % location of lesions showed that most occurred in the 5-7-kHz region, at & just above the upper edge of the OBN. Clusters of lesions were also found around 8 & 12 kHz. A cluster was present at & just below the lower edge of the OBN, as well as in the 1.5-kHz region. For the 0.5-kHz OBN, a histogram of the % location of lesions showed clusters at 0.25, 0.75 & 1.5 kHz in the apical half. In the basal half, the pattern was very similar (Pearson's r=0.69) to that seen with the 4-kHz OBN. The distribution of basal-turn lesions suggests that the 4-kHz & 0.5-kHz OBN are damaging that region of the cochlea in the same way. [Description provided by NIOSH]
• Subjects:
  Animals Hearing Hearing Loss Hearing Loss, Noise-Induced Laboratories Noise Occupational Health Safety
• Keywords:
  Exposure-levels Hearing-disorders Hearing-loss Laboratory-animals Noise-exposure Noise-induced-hearing-loss
• ISSN:
  0742-3152
• Publisher:
  Association for Research in Otolaryngology
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Maryland ; Missouri ; New Jersey ; OSHA Region 2 ; OSHA Region 3 ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  10-11
• Volume:
  29
• NIOSHTIC Number:
  nn:20041573
• Citation:
  Abstr Midwinter Res Meet Assoc Res Otolaryngol 2006 Feb; 29:10-11
• Editor(s):
  Santi PA
• Federal Fiscal Year:
  2006
• NORA Priority Area:
  Disease and Injury: Hearing Loss
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Abstracts of the 29th Midwinter Research Meeting of the Association for Research in Otolaryngology, Febuary 5-9, 2006, Baltimore, Maryland
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:af54802311696a1549d404c6e32672fbbd7a1092e07476a78b3b728cc1f381f2adfb9ceeb406e008eb3c1e5554bd64576bb135b1d79be21e36e1bbd9c46062cb
• Download URL:
  https://stacks.cdc.gov/view/cdc/194107/cdc_194107_DS1.pdf
• File Type:
  [PDF - 544.22 KB ]