This keyboard actually has 2 rows of keys, like an organ, as well as a pedal keyboard. The upper keyboard, played with the right hand will generate the melody, while the lower keyboard, played with the left hand, determines what speech-synthesized consonants are to be used for that note. The pedal keyboard,
finally, determines the vowels.
Just as sound can be tailored by a keyboard with regard to pitch and timbre, this keyboard can add the capability for any number of different voice styles, (rock, country, opera, etc).
I think that the right hand would be easier to learn...it might actually take more than one person to operate the word-generating part.