Accession Number : AD0281773

Title :   CALIBRATION AND FREE FIELD EVALUATION OF A PRESSURE GRADIENT MICROPHONE,

Corporate Author : OKLAHOMA STATE UNIV STILLWATER RESEARCH FOUNDATION

Personal Author(s) : Thurston ,George B. ; Heiserman,Russell L.

Report Date : JUL 1962

Pagination or Media Count : 19

Abstract : The design, calibration procedure, and evaluation in a free field for a co de ser type pressure gradient microphone are describ d. Procedures wer carried out for determination of both magnitude and phase of the pressure gradient. The microphone responded to the differential action of the pressure at two closely spac d field points as communicated by two small probe tubes to either side of a sensing metal diaphragm. By means of a coupling chamber calibration proce ure it was po sible to obtain a sensitivity factor and an error factor which may be us d both to describe the precision of the internal structure of the micropho e as well as to corr ct for its i perfections. The free field studies analyzed the directional characteristics and resolution capabilities of the microp one. The radia ion c racteri tic of a circular orifice in a plane baffle as measured with the gradient microphone are compared with those predicted by simple field theory with r g rd o the r l ionship between the pressure gradient magnitude and phase a d the pressure magni ude and phase. (Author)

Descriptors :   *COMMUNICATION EQUIPMENT, *MICROPHONES, ACOUSTICS, CALIBRATION, CAPACITORS, DESIGN, ERRORS, MATHEMATICAL ANALYSIS, PRESSURE, SENSITIVITY, TEST METHODS, TESTS

Distribution Statement : APPROVED FOR PUBLIC RELEASE