  We report the experimental observation of $1/f$ fluctuations in three
different turbulent flow configurations: the large scale velocity driven by a
two-dimensional turbulent flow, the magnetic field generated by a turbulent
swirling flow of liquid sodium and the pressure fluctuations due to vorticity
filaments in a swirling flow. For these three systems, $1/f$ noise is shown to
result from the dynamics of coherent structures that display transitions
between a small number of states. The interevent duration is distributed as a
power-law. The exponent of this power-law and the nature of the dynamics
(transition between symmetric states or asymmetric ones) select the exponent of
the $1/f$ fluctuations.
