This invention relates to an electronic musical instrument capable of producing musically rich performance tones by imparting random characteristics or casualness to the pitch, color and volume envelope to the musical tones generated by the musical instrument. 
In an electronic musical instrument, the pitch of the generated musical tone and the generation of the tone are generally controlled by key informations which are generated in accordance with the depressed keys of a keyboard.  The pitch variation, the tone color and the volume envelope of the generated musical tone are set and controlled by various operating means, for example a pitch adjusting lever, a tone adjusting lever, etc, which are mounted on a panel of the musical instrument.  However, since these operating levers are mounted on the panel of the musical instrument the player can not operate them freely during performance, and usually the player must operate them before the performance.  Accordingly, during the performance the musical tones are generated always under the same conditions, (that is the same pitch variation, the same tone color and the same volume envelope) with the result that the generated musical tones lack variety, thus producing extremely monotoneous tones.