  NA44 uses a 512 channel Si pad array covering $1.5 <\eta < 3.3$ to study
charged hadron production in 158 A GeV Pb+Pb collisions at the CERN SPS. We
apply a multiresolution analysis, based on a Discrete Wavelet Transformation,
to probe the texture of particle distributions event-by-event, by simultaneous
localization of features in space and scale. Scanning a broad range of
multiplicities, we look for a possible critical behaviour in the power spectra
of local density fluctuations. The data are compared with detailed simulations
of detector response, using heavy ion event generators, and with a reference
sample created via event mixing. An upper limit is set on the probability and
magnitude of dynamical fluctuations.
