n…are multimodal interfaces combining speech recognition and gesture recognition. n...are the most pervasive and thoroughly studied multimodal input combination to date. n…represent the most accessible multimodal combination as microphones and touchpad or pen input devices are widely available and often packaged with current personal computers and laptops. Also, gesture based input can ;;;;;;;also be provided via conventional mouse input devices. n...design and implementation guidelines are far from full maturity leaving much opportunity for research possibilities.