Method of and apparatus for producing musical instrument keyboard-controlled pitch variation, tone alteration and the like

A method of introducing tone variations into the sound created by the impact of downwardly depressed longitudinally extending planar playing key mechanisms in musical instruments, that comprises, depressing the key mechanisms individually;

• moving each key mechanism with individual freedom of longitudinal movement backward and forward substantially in the plane of the keys;
• limiting such backward and forward movement within predetermined limits;
• and responding to said backward and forward movement of the downwardly depressed key mechanisms to introduce corresponding pitch variations, tone alternations and related effects, said pitch variations being separately and differently generated for the individual key mechanisms in accordance with the degree of backward and forward movement of the corresponding key mechanisms.