  We present an inelastic light scattering study of single crystalline
(La$_{1-y}$Pr$_y$)$_{1-x}$Sr$_{x}$MnO$_3$ ($0\leq x\leq0.14$,$y=0$ and
$x=1/8$,$0\leq y\leq0.5$). A giant softening up to 20 - 30 cm$^{-1}$ of the
Mn-O breathing mode has been observed only for the ferromagnetic insulating
(FMI) samples ($0.11\leq x \leq 0.14$) upon cooling below the Curie
temperature. With increasing Pr-doping the giant softening is gradually
suppressed. This is attributed to a coupling of the breathing mode to orbital
polarons which are present in the FMI phase.
