  We present multi-wavelength scatter broadening observations of 47 pulsars,
made with the Giant Metre-wave Radio Telescope (GMRT), Ooty Radio Telescope
(ORT) and Long Wavelength Array (LWA). The GMRT observations have been made in
the phased array mode at 148, 234, and 610 MHz and the ORT observations at 327
MHz. The LWA data sets have been obtained from the LWA pulsar data archive. The
broadening of each pulsar as a function of observing frequency provides the
frequency scaling index, $\alpha$. The estimations of $\alpha$ have been
obtained for 39 pulsars, which include entirely new estimates for 31 pulsars.
This study increases the total sample of pulsars available with $\alpha$
estimates by $\sim$50\%. The overall distribution of $\alpha$ with the
dispersion measure (DM) of pulsar shows interesting variations, which are
consistent with the earlier studies. However, for a given value of DM a range
of $\alpha$ values are observed, indicating the characteristic turbulence along
each line of sight. For each pulsar, the estimated level of turbulence,
$C^{2}_{n_e}$, has also been compared with $\alpha$ and DM. Additionally, we
compare the distribution of $\alpha$ with the theoretically predicated model to
infer the general characteristics of the ionized interstellar medium (ISM).
Nearly 65\% of the pulsars show a flatter index (i.e., $\alpha < 4.4$) than
that is expected from the Kolmogorov turbulence model. Moreover, the group of
pulsars having flatter index is typically associated with an enhanced value of
$C^{2}_{n_e}$ than those with steeper index.
