A shift-by-speech transmission system allows a driver or a motorcyclist to choose a desired gear by voice commands. Conventional sequential semi-manual shifting only allows the driver to shift one gear up or down from a current gear using a gearshift lever or a paddle shifter. The level of driver engagement in existing semi-manual shifters leaves much to be desired for many auto enthusiasts. An intuitive and engaging shift-by-speech technology disclosed in the present invention, called “VoiceShift”, allows the driver or the motorcyclist to switch gears by voice commands. VoiceShift also allows the driver or the motorcyclist to skip gears to up-shift and down-shift as desired, as long as a desired gear does not result in mechanically-detrimental situations.