a keyboard type electronic musical instrument in which note data and duration data are read out from a memory in accordance with the progress of a musical piece , and a control circuit turns on display devices provided for individual keys on a keyboard in response to note data , thus training a player to operate keys specified by the display devices . the control circuit counts each instance of noncoincidence between a key represented by the note data and an operated key on the keyboard , and obtains deviations between a key operation timing defined by duration data and the timing of key operation on the keyboard . after the end of a performance , the control circuit informs the player of the number of the mis - key operations or the accumulation of key operation timing deviations by means of the display devices . a number of display devices corresponding to the accuracy of the performance are lit .