NOISE ATTENUATION CHARACTERISTICS OF THE AUTOMATIC AND PRECISION COMPANY'S APM-XL EARPHONE CUSHION.
Abstract
Two sets of earphone cushions (APM-Xl) manufactured by the Automatic and Precision Manufacturing Company were evaluated as to their noise attenuation characteristics by methods reported previously on various personnel noise attenuation characteristics by methods reported previously on various personnel noise protective devices. The physical and subjective measures have been described in detail in Joint Project Report NM 001 064.01.16 and Special Reports 55-2 and 55-6 (Reports 4 and 5 of TED PEN 1403). The physical measures were obtained from the output of a miniature condenser microphone serving as an 'artificial ear' shock mounted within a plaster 'dummy' head. Listener threshold measures were obtained from the reported judgments of 10 observers who had received training in the listening tasks. The four listening conditions included (a) pulsed discrete frequency threshold shifts, (b) pulsed wideband and octave-bands of noise threshold shifts, (c) Spondee word reception threshold shifts, and (d) an attenuation to threshold of an 800 cps pulsed-tone and Spondee words presented at an arbitrary signal level of 114 db at the ear canal while the observer was in a masking ambient noise environment of 116 db of recorded HUP-2 noise. The AMP-Xl earphone cushion in an HS-33 headset (PDR-3) does not attenuate as well as personnel some of the noise protective devices previously evaluated. However, for frequencies above 4000 cps the mean threshold values indicate equal or better attenuation than the V-51R ear warden. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 1955
- Accession Number
- AD0622043
Entities
People
- Gilbert C. Tolhurst
Organizations
- Ohio State University