Frequency dependence of sound transmitted from an airborne source into the ocean
By: H. Medwin & R.A. Helbig
Contributors: Helbig, R. A.; Naval Postgraduate School (U.S.)
Publisher: Naval Postgraduate School
Published: 1972
Place of publication: Monterey, Calif
Language: eng
Number of pages: 59
Subjects: Underwater acoustics; Mathematical models; Seawater; Acoustics; Airplanes; Noise; Ocean-atmosphere interaction; Helmholtz equation
Description: The predicted dependence of sound transmission on the statistics of the randomly-rough interface between dissimilar fluids has been studied by use of the Helmholtz Integral. The predictions have been verified for radiation from a helicopter hovering, and slowly moving, over the sea, for frequencies to 1000 Hz for a wide range of slowly moving, over the sea, for frequencies to 1000 Hz for a wide range of surface acoustical roughnesses. The roughness parameters are the rms height of the surface, propagation constant, speed of propagation and angle with the normal, respectively. The transmission change of sound pressure as a function of frequency is presented for several conditions of an SH3-D helicopter hovering and flying over or near an array of microphone and sonobuoy hydrophones. (Author)
Notes: Cover title.

"NPS-61Md72051A."

"15 May 1972."

DTIC Identifiers: SH-3 aircraft, Helmholtz equation.

Author9s) key words: Sound refraction, rough-surface transmission.

Includes bibliographical references (p. 51)

"Approved for public release; distribution is unlimited."

Technical report; 1972.