Abstract: In a guitar or the like where fretting is detected by ultrasonic signals emitted by a transducer bridge and reflected at a point of each string held against a fret, and the same transducer bridge is responsive to audible frequency string vibration induced by a player, a damper bridge selectively dampens propagation of lower frequency vibrations from a note triggering string section adjacent to the bridge to a note selecting string section extending over the fretted neck, thereby minimizing intereference between fret detection and note triggering functions using a single set of string and a single acoustic transducer for each string.

Abstract: Note bending in a MIDI interfaceable fretted string instrument is detected by sensing relative phase shifting in an echo return of an ultrasonic acoustic signal propagated along each string. The delay between the propagated signal and echo return is indicative of the musical note obtainable by playing the string. The propagation and sensing may be accomplished by means of a single piezoelectric transducer coupled to each string, and the same transducer can sense string vibration in the audible frequency range indicative of the timing and amplitude of a musical note played on the string.