Article,
Spherical acoustical holography of low-frequency noise sources
Applied Acoustics, (1996)
Abstract
The performance of near-field reconstruction at low frequency using
spherical holographic techniques is investigated. The spherical Hankel
function with small argument (near-field and low frequency) has divergent
behaviour in the near-field. This divergent phenomenon influences
the precision of holographic reconstruction. Two computer simulations
based on the derived equations are used to demonstrate the capability
of holography to construct the source surface pressure and particle
velocity for noise source identification.The results of multipole
source simulation show that the precision of backward holography
to the near-field depends on using the optimum order of holographic
wave. Analysis of another simulation shows that more precise reconstruction
of source surface pressure and particle velocity can be obtained
from original pressure data at a smaller radius.
