Disclosed are systems, methods, and non-transitory computer-readable storage media for altering pitch of a note played on a musical instrument keyboard of a touch-sensitive electronic display. An exemplary method includes playing a note of a key of the keyboard on the touch-sensitive display touched by a user. The method includes continuously altering the pitch of the played note as the user slides a point of contact on the touch-sensitive display horizontally from the key being played across adjacent keys to a second key, in accordance with the keys being contacted during the sliding of the point of contact. In a further aspect, the method includes detecting motion of user contact in a direction other than horizontally across keys of the keyboard, such as vertical, and activating a sound effect in addition to pitch alteration in response to the detection. Example sound effects include tremolo, vibrato, echo, and sound filter effects.