  The aim of the study is to demonstrate that some methods are more relevant
for implementing the Real-Time Nearfield Acoustic Holography than others. First
by focusing on the forward propagation problem, different approaches are
compared to build the impulse response to be used. One of them in particular is
computed by an inverse Fourier transform applied to the theoretical transfer
function for propagation in the frequency-wavenumber domain. Others are
obtained by directly sampling an analytical impulse response in the
time-wavenumber domain or by additional low-pass filtering. To estimate the
performance of each impulse response, a simulation test involving several
monopoles excited by non stationary signals is presented and some features are
proposed to assess the accuracy of the temporal signals resulting from
reconstruction processing on a forward plane. Then several inverse impulse
responses used to solve the inverse problem, which consists in back propagating
the acoustic signals acquired by the microphone array, are built directly from
a transfer function or by using Wiener inverse filtering from the direct
impulse responses obtained for the direct problem. Another simulation test is
performed to compare the signals reconstructed on the source plane. The same
indicators as for the propagation study are used to highlight the differences
between the methods tested for solving the Holography inverse problem.
