The Physics of Musical Scales

Dr. Dallin S. Durfee
Department of Physics and Astronomy
Brigham Young University

There are physical reasons we use the scales we do, and the study of the physics of musical scales can enliven physics courses.  The application of some basic physics principles can give insight into why different musical scales have been used throughout history, why composers such as Bach avoided writing music in certain keys, and why some chords sound consonant and others dissonant.  I will discuss the history of musical scales and the physics behind them, with an emphasis on four historically important scales: twelve-tone equal temperament, Pythagorean, quarter-comma meantone, and Ptolemaic just intonation. I will present an easy way for students and teachers to directly experience the qualities of different scales using a MIDI synthesis program I have written called Temperament Studio.