Accession Number:

ADA243174

Title:

The Effect of Impulse Presentation Order on Hearing Trauma in the Chinchilla

Descriptive Note:

Corporate Author:

ARMY AEROMEDICAL RESEARCH LAB FORT RUCKER AL

Report Date:

1991-09-01

Pagination or Media Count:

70.0

Abstract:

Existing criteria for exposure to impulse noise do not provide any explicit means for evaluating exposures for which the peak SPL Sound Pressure Level of the impulses varies in any given exposure day. Approaches to evaluating such exposures have included the application of a proportional dose method such as used with continuous noise or use of an average level. Implicit in these approaches is the assumption that the order in which a sequence of variable intensity impulses is presented is not important. This same assumption is also implicit in any energy-based exposure criteria. This report presents results of a pilot experiment designed to test the validity of this assumption. Two groups of chinchillas were exposed to a sequence of 100 impulses. One group received 90 exposures at 138-dB peak SPL impulses followed by 10 exposures at 146-dB peak SPL impulses the second group received the same series of impulses but in reverse order. Results from these two groups were compared to results of 100 exposures at 147-dB peak SPL impulses from a report by Patterson et al., 1986. The 139-dB peak SPL exposure had the same total energy as the two variable intensity exposures. Results of the three equivalent energy exposures showed that exposures having equal energies could produce statistically different levels of hearing trauma. However, while the mean data were very suggestive in showing an effect of the presentation order, this result did not hold up to statistical analysis because of a large intersubject variability.

Subject Categories:

  • Biology
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE