Research Summary
Electric guitars produce sound not because the instrument's vibration results in acoustic radiation, but because the vibration of the strings is converted to an electrical signal which is amplified and sent to a loudspeaker. The transducers which convert the string vibration to electrical signals in most electric guitars are magnetic pickups which measure the string velocity according to Faraday's Law of electromagnetic induction. While magnetic pickups are the norm, there are other methods of detecting the string motion. Optical pickups use a small beam of infrared light to detect the position of the string and thus measure the string's displacement as a function of time. Piezoelectric pickups in the bridge of the guitar measure the force the strings exert on the bridge. This research project is investigating the differences in the signals measured by each of these three pickups (magnetic=velocity, optical=displacement, piezoelectric=force) with application to the uses of different types of pickups and differences in the sound quality they produce. Since the time signals are very different, the frequency content is also noticeably distinct for the various pickups.