Much controversy has surrounded the different 4 speaker implementations of positional audio. Creative Labs has both front and rear-speaker HRTF's for true separation while Aureal uses volume panning in the rear. Sensaura, on the other hand, delivers a truly impressive sound field by addressing a frontal and rearward sound hemisphere. Using transaural acoustic crosstalk cancellation, MultiDrive accurately blends the two regions for optimal 4-speaker performance (crosstalk cancellation makes sound more accurate by eliminating the sound heard from the right speaker by the left ear and vice-versa).