I just reduced a harshness in vocals on my very cheap speakers (which otherwise sound great but shall remain nameless, for now) by pacing a square of open cell foam in front of the driver. Experiment with placement on the midrange or tweeter. Hey, it's free and it made a difference that was worthwhile. The speakers are now very listenable.
They are Radio Shack Minimus 11. HA!
They are Radio Shack Minimus 11. HA!