Recently performed inhomogeneous stress experiments in KSCN showed for the first time the appearance of a Heat-Diffusion Central Peak in a macroscopic elastic susceptibility. In the meantime we have observed the presence of entropy fluctuations also in other crystals. In all these inhomogeneous (q ≠ 0) measurements the corresponding relaxation function is a Debye one. In contrast, in a usual macroscopic homogeneous field ( q = 0) experiment the crossover between the isothermal and the adiabatic limit differs significantly from the Debye behaviour. Here we present Three Point Bending (Hz-region, q ≠ 0) and ultrasonic (MHz-region) measurements, performed recently on EAMC-layered crystals, showing that with elastic constant measurements the dynamics from order parameter fluctuations and entropy fluctuations can be well separated. We outline a phenomenological theory which describes a Heat-Diffusion Central Peak in macroscopic homogeneous (q = 0) and inhomogeneous (q ≠ 0) field experiments near ferroic phase transitions.