  Noise power spectra in spatially extended dynamical systems are investigated,
using as a model the Complex Ginzburg-Landau equation with a stochastic term.
Analytical and numerical investigations show that the temporal noise spectra
are of 1/f^a form, where a=2-D/2 with D the spatial dimension of the system.
This suggests that nonequilibrium order-disorder phase transitions may play a
role for the universally observed 1/f noise.
