An investigation of some phenomena relating to aural detection of airplanes

Harvey H. Hubbard, Domenic J. Maglieri
Sep 1958

An investigation was conducted to determine the effect of modifications made in the propulsion system of a single-engine airplane to substantially reduce its external noise and, thereby, to evaluate the significance of the external noise level of an airplane with regard to the problem of its detection by ground observers. Conventional noise-level measurements consisting of broad- and narrow-band frequency analyses were made for static tests on the ground.

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