Apparatus for encephalic insonication, comprising a transducer array configured to safely insonicate a field in a human body of a size comparable to the spatial extent of the array itself. The array comprises a plurality of acoustic transducers arranged in a polygonal configuration and energized in subsets at frequencies between 200 and 400 kHz. A relatively uniform insonication of a field comparable in size to that of significant anatomical regions of the brain is obtained by driving the transducers in each subset in opposed phase relationship during at least part of the interval during which they are active. A pulsed driving scheme enables minimization of heating effects while providing significant therapeutic treatment. The apparatus is useful both with and without additional lytic agents.
