Accession Number : AD0289675

Title :   6570 AMRL HIGH INTENSITY PURE TONE SOUND GENERATOR CAPABILITIES DURING ANECHOIC AND REVERBERANT OPERATION

Corporate Author : AEROSPACE MEDICAL RESEARCH LABS WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : DURAND,FREDERICK L.

Report Date : NOV 1962

Pagination or Media Count : 1

Abstract : A high intensity siren was constructed. Although this sound source was designed to cover the frequency range from 10 c to 200 kc, this evaluation was made to establish its capabilities within the audio-frequency range. In the choic chambers, *Sound, Auditory signals, Noise, Audiofrequency, Instrumentation, Compressed air, Microphones, Energy, Power, Pressure, Experimental data, Analysis. Identifiers: Graphics.A high intensity siren was constructed. Although this sound source was designed to cover the frequency range from 10 c to 200 kc, this evaluation was made to establish its capabilities within the audio-frequency range. In the anechoic chamber the maximum SPL was recorded at 2.5 ft. from the tip of the cone and at frequencies above 2500 c levels of 160 to 165 db were recorded. The decrease in level beyond that point closely followed the ''inverse square law'', i.e. 6 db drop per doubling of distance. It was found that significant side lobes were present in the wave front at the lower frequencies but at higher frequencies, the directivity pattern reduced to a single centrally located lobe. The siren power output was determined to be approximately 300 watts at a rotor pressure of 3 psig except for the region near 2600 c where the power output is reduced by about half. An average sound pressure level of 140 db was achieved in a reverberation chamber (approx. 4,000 cubic feet volume) for the frequency range from 1 to 10 kc. (Author)

Descriptors :   *ANECHOIC CHAMBERS, *SOUND, *SOUND GENERATORS, ANALYSIS, AUDIO FREQUENCY, COMPRESSED AIR, ENERGY, EXPERIMENTAL DATA, INSTRUMENTATION, MICROPHONES, NOISE, PORPHOBILOGEN, PRESSURE, ACOUSTIC SIGNALS

Distribution Statement : APPROVED FOR PUBLIC RELEASE