We report multi–frequency measurements of scatter broadening times for nine highly dispersed pulsars over a wide frequency range ( 0.6 – 4.9 GHz ) .
We find the scatter broadening times to be larger than expected and to scale with frequency with an average power-law index of 3.44 \pm 0.13 , i.e .
significantly less than that expected from standard theories .
Such possible discrepancies have been predicted very recently by Cordes & Lazio .