Thermal effects on crackling noise

We present a systematic study of thermal effects on crackling noise. We identify three different scaling regimes in the power spectra, and give explicit expressions for the corner frequencies separating the different regimes. We show a new low-frequency regime arising from hierarchical dynamics induced by the finite temperature and show that our predictions are universal and apply to generic crackling systems. We suggest that thermal effects are responsible for several ubiquitous, yet unexplained, behavior in a number of crackling systems.