THE NEARFIELD ACOUSTICAL-HOLOGRAPHY (NAH) EXPERIMENTAL-METHOD APPLIEDTO VIBRATION AND RADIATION IN LIGHT AND HEAVY FLUIDS

This paper presents recent experimental and theoretical research in th e area of nearfield acoustical holography (NAH) aimed specifically at the study of the vibration, radiation and scattering from acoustic sou rces under the water and in the air. Development of the theory in vari ous geometries is presented, hopefully enabling the application of the method to the experimental analysis of a wide variety of sources. The shape of the actual source dictates which of the geometries discussed in this paper should be considered. Furthermore, we discuss NAH for b oth the external problem, which applies to externally radiating source s such as aircraft engines and submarines; and the internal problem wh ich encompasses room acoustics including noise control in enclosed spa ces such as in the interior of an aircraft fuselage. In the latter cas e we present some new Green functions specifically for the application of NAH to a cylindrical cavity. Published by Elsevier Science Ltd.