Accession Number:

AD0689404

Title:

INVESTIGATION OF CONTACT MICROPHONES FOR USE IN HIGH AMBIENT NOISE FIELDS

Descriptive Note:

Corporate Author:

BALDWIN PIANO CO CINCINNATI OH

Personal Author(s):

Report Date:

1957-10-01

Pagination or Media Count:

52.0

Abstract:

The vibration spectrum and level of speech from different anatomical locations was measured using contact microphones adapted for this purpose. This information was used to select the optimum anatomical locations for picking up speech in extremely noisy 140 db re. 0.0002 dyne sq cm sound fields near jet engines. On the basis of this preliminary research several microphone-noise shield systems for use at selected anatomical locations were developed. Articulation tests of contact microphone-noise shield systems were conducted in a 120 db jet noise spectrum. Unsatisfactory articulation scores were obtained with these systems even with optimum electrical equalization of speech signal, anatomical location and seal around the microphone. A noise canceling system employing a pressure gradient microphone M-76 located in close proximity to the skin provided satisfactory speech intelligibility in a 120 db jet noise spectrum. On the basis of available data it appears that this noise cancelling microphone system located on the forehead or neck area would provide satisfactory communication in a 140 db jet noise.

Subject Categories:

  • Acoustics
  • Non-Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE