Fluctuations in the phase velocity of fluctuations have been computed from floating potential fluctuations in the JET plasma boundary region. Experimental results reinforce the idea that, in some conditions, fluctuations in the phase velocity are linked with fluctuations in radial - poloidal electric fields opening the possibility to investigate turbulent transport in the plasma core region from measurements of density fluctuations. These results indicate that time dependent radial electric fields and ExB shearing rates might be computed in the plasma core from measurement of density fluctuations.