  Measurements of particles emitted from collisions of heavy ions at
relativistic energies show evidence for temperature-fluctuations on the
freeze-out surface of the expanding fireball. These can be understood as
remnants of the density inhomogeneities in the initial collision overlap
region. In this paper we present an analysis of heavy-ion collisions analogous
to the analysis of the cosmic microwave background radiation. We use data on
transverse momentum correlations to extract a power-spectrum from heavy-ion
collisions and use a Glauber model for eccentricity to extract the transfer
function needed to produce the observed correlations. We also discuss the
acoustic signal, the sound that an observer inside the matter would hear.
