NOISE ATTENUATION CHARACTERISTICS OF THE MINE SAFETY APPLIANCE 2A INSERT TYPE EAR PLUG.
Abstract
An insert type ear plug, Mine Safety Appliance 2A, was evaluated as to its noise-tone-speech attenuation characteristics. Two general techniques were employed: (1) Physical measures were obtained from the output of a miniature condenser microphone serving as an artificial ear mounted within a manikin plaster head; and (2) Listenerobserver judgments of threshold shift were made occasioned by the protective device, as the stimuli were presented ambiently, listening binaurally. Ten individuals made judgments on three listening tasks which included: (a) pulsed pure tones at eight discrete frequencies, with each individual making three judgmental series at successive time intervals (30 measures each frequency); (b) pulsed wide-band and octave-bands-ofnoise threshold shifts, one series of observations per individual (10 measures each noise band); and (c) a series of observations concerning Spondee word threshold shifts, one series per individual (10 measures). The discrete frequency threshold measures were conducted, inasfar as possible, to conform to the CHABA Report on 'Standard Method for the Measurement of the Real-Ear Attenuation of Ear Protectors.' As measured by the output of the artificial ear the MSA 2A does not afford as much attenuation as the V-51R measured previously. However, the relative threshold shift measures on the three listening tasks yielded increased attenuation values for the MSA 2A over those found for the V-51R. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1956
- Accession Number
- AD0622066
Entities
People
- Gilbert C. Tolhurst
Organizations
- Ohio State University