Comment 1 for bug 896161

I find sonic weapons dodgy generally. For example, the 'target' always takes less damage than the units that the wave passes through (presumably because damage is dealt by the passing wave, which doesn't pass all the way through the target).

My guess for the reported issue is that the wave is designed not to activate its damage until leaving the firing cell, thus not damaging the firer. But in this case the wave is reversed, so the target cell doesn't take damage and the firing cell potentially could. Just speculation though as I'm not in front of my PC right now.