ACOUSTIC NOISE CANCELLING TECHNIQUES FOR DOMED HELMETS.
Abstract
The specific objective was study of the feasibility of noise cancelling devices for producing a quiet zone within the confines of a domeshaped space suit helmet. Little practical use has been made of the noise-cancelling principle because of the difficulty of constructing adequate equipment, and because operation is possible only for limited frequency ranges and small space volumes. The conclusion from both theory and experiment was that the complex sound field inside of a helmet makes it impossible to secure effective noise reduction by noise cancellation. Some alternate noise reduction methods are discussed. The tests involved construction of an artificial head featuring binaural pickup through microphones in the ear positions. Construction and calibration of the head are described. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1963
- Accession Number
- AD0424179
Entities
People
- Martin S. Tatch
- William B. Snow