  We observed a dramatic peak in the 1/f noise at the metal-insulator
transition (MIT) in low-Tc manganites. This many-orders-of-magnitude noise
enhancement is observed for both polycrystalline and single-crystal samples of
La{5/8-y}Pr{y}Ca{3/8}MnO{3} (y=0.35-0.4) in zero magnetic field and
Pr{1-x}Ca{x}MnO{3} (x=0.35-0.5) in magnetic field. This observation strongly
suggests that the microscopic phase separation in the low-Tc manganites causes
formation of a percolation network, and that the observed MIT is a percolation
threshold.
