Accession Number : ADA801483


Title :   Design of an Automatic Octave Sound Analyzer and Recorder


Corporate Author : HARVARD UNIV CAMBRIDGE MA CRUFT LAB


Personal Author(s) : Rudmose, H W ; Ericson, Harold L ; Dienel, Hans F


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a801483.pdf


Report Date : 21 Nov 1942


Pagination or Media Count : 82


Abstract : An automatic octave sound apparatus is described which is suitable for analyzing and measuring sound in combat vehicles. An Ra-277 G sound frequency analyzer when used with a suitable graphic level recorder, permitted analysis of noise over a frequency range from 40 to 10,000 cycles per second by means of a 5-cycle wide or 200-cycle wide band pass filter. It was learned that airplane noise was produced by the propeller, by the engine exhaust, and by air leaks and aerodynamic flow. A complete system composed of a dynamic microphone, an octave band-pass filter set, a sound level meter, an automatic graphic level recorder, a battery power supply, and a hand-held remote control unit is described that determines either manually or automatically, sound levels in airplanes by octave bands.


Descriptors :   *SOUND ANALYZERS , AERIAL PROPELLERS , AERODYNAMICS , AIRCRAFT , AIRCRAFT EXHAUST , AIRCRAFT NOISE , COMBAT VEHICLES , ELECTRIC BATTERIES , ELECTRONIC EQUIPMENT , MEASURING INSTRUMENTS , POWER SUPPLIES , RECORDING SYSTEMS , REMOTE CONTROL


Distribution Statement : APPROVED FOR PUBLIC RELEASE