Experimental Study of Outdoor Propagation of Spherically Spreading Periodic Acoustic Waves of Finite Amplitude.

Theobald, Mark A.

doi:10.21236/ada039020

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…Nearfield sound pressure measurements along the radiation axis do not fully agree with computed values for similar piston radiators 10,11 . Measurements made in the nearfield of single, baffled loudspeakers can be used to predict the farfield characteristics of the sound field 13 .…”

Section: Introductionmentioning

confidence: 69%

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Radiated sound and the geometric nearfield size

Kuntz¹

2008

Noise Control Eng. J.

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The sound field radiating from a finite-sized body has two distinct regions of acoustic pressure variation. The geometric farfield is the region far from a finite-sized radiator, where the sound pressure level increases at a rate of 6 dB with every halving of distance from the body (spherical spreading). The geometric nearfield is the region close to the radiator where the 6 dB relation does not hold. The nearfield size depends on the frequency and the radiator size. In most cases, the geometric nearfield is small enough that the measurement point is in the farfield. When the radiation surface is large and the frequency high, the geometric nearfield is large and a measurement position may be within the nearfield. Because of the nearfield pressure characteristics, nearfield pressure measurements should not be extrapolated to the farfield. This paper contains a discussion of the different estimates of the nearfield size of coherent radiators and, through examples of pressure measurements illustrating the nearfields of variously-shaped radiators, shows that a simple equation may be used to calculate the on-axis, nearfield size of a coherent radiator.

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Section: Introductionmentioning

confidence: 69%

“…13 was determined by evaluating Eqns. (9) and (10). The calculated values were matched to the measured data in the farfield.…”

Section: Rectangular Horn Arraymentioning

confidence: 99%

Radiated sound and the geometric nearfield size

Kuntz¹

2008

Noise Control Eng. J.

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Advances in atmospheric acoustics

Brown¹,

Hall²

1978

Reviews of Geophysics

153

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We give a detailed review of developments in atmospheric acoustics of the last decade. These developments include new ways to use refractive effects, studies of phase and amplitude fluctuations during propagation of sound along a path, nonlinear effects near high‐powered acoustic antennas, problems related to noise, insights into large‐scale atmospheric processes gained from infrasound, applications dependent on the Doppler frequency shift, and hybrid devices using both acoustic and electromagnetic waves. The introduction of the echosonde approximately 10 years ago results in the considerable emphasis given to advances in active acoustic remote sensing of atmospheric structure.

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Experimental Study of Outdoor Propagation of Spherically Spreading Periodic Acoustic Waves of Finite Amplitude.

Cited by 2 publications

References 6 publications

Radiated sound and the geometric nearfield size

Radiated sound and the geometric nearfield size

Advances in atmospheric acoustics

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