However, as with anything, there are limitations. Simply put, it attempts to cancel the crosstalk from the right speaker to the left ear and vice versa, by isolating the sounds from the left speaker to the left ear and the right to the right ear. While this can be effective, it normally results in a very narrow sweet spot. In many systems, if listeners simply turn their heads, or move as little as 3 cm to one side or the other, the entire virtual effect can be destroyed. This is not practical in a home theater, especially if more than one person is in the audience.
Some systems also use timing and phase manipulation, which further narrows the sweet spot.
It should be pointed out, though, that even multispeaker surround systems have a sweet spot. Sit too near any of the speakers, and the surround effect will be grossly distorted. By relying on HRTF-based processing and judiciously avoiding the use of interaural crosstalk cancellation and time and phase manipulation, a virtualizer can be designed that provides the largest possible sweet spot, does not compromise sound quality, and creates a realistic, immersive sound field. Further, this type of system typically requires less processing power. The first time someone listens to a virtualizer, the experience is bound to be surprising.