Systems, methods, and apparatuses may be used to determine fretted positions associated with a stringed instrument. Stringed instruments may be used for interfacing with at least one musical synthesizer interface. A specially-modified stringed musical instrument or system applied to a stringed musical instrument may be used to determine where a guitarist is pressing guitar strings against guitar frets (e.g., ‘stopped positions’ or ‘fretted positions’) without resorting to sending electrical current down the strings or having segmented frets. Special techniques may be used to determine when a pluck of a string occurs. A guitarist may be allowed to play a guitar in a normal manner and control a musical synthesizer or other sound generating device with the same level of predictability that keyboard players have enjoyed for years.