Accession Number:

AD0672774

Title:

NUMERICAL EVALUATION OF THE SERIES EXPANSION METHOD FOR THE PREDICTION OF THE FAR FIELD INTENSITY FROM NEAR FIELD CROSS-POWER MEASUREMENTS

Descriptive Note:

Scientific rept.

Corporate Author:

PARKE MATHEMATICAL LABS INC CARLISLE MA

Personal Author(s):

• Butler, John L.
• Moran, Dorothy A.

Report Date:

1968-08-01

Pagination or Media Count:

23.0

Abstract:

An evaluation of a series expansion method for predicting the far- field from near-field cross-power measurements of partially coherent sound fields is given. This series method is based on an expansion in spherical wave functions truncated to include only the number of terms equal to the number of near field measuring points which need not be restricted to the usual separable surfaces. The evaluation is through a set of numerical examples where the predicted far field is compared with the exact far field from a theoretical source of partially coherent sound. It is shown that good results can be obtained for incoherent, partially coherent, and coherent sound fields.

Descriptors:

• *SOUND TRANSMISSION
• INTENSITY
• MATHEMATICAL PREDICTION
• MEASUREMENT
• NUMERICAL ANALYSIS
• POWER
• SERIES(MATHEMATICS)
• SOUND

Subject Categories:

• Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE