Pitch drift as a result of just intonation
Patrick K. Mullen · The Journal of the Acoustical Society of America · 2000
The most easily recognized difficulty with just tuning is the large and confusing array of pitches that must be made available on a keyboard instrument in order to allow modulation to several keys. A given note name may have more than one pitch associated with it, sometimes several, depending on the context in which it is used. Using computer-generated instruments that provide a limitless supply of unique pitches, just intervals can be used exclusively and explored thoroughly. When applied to Giovani Gabrieli’s Sonata Pian’ E Forte, the strict use of just tuning forces the pitch center to drift lower as the music progresses. When pitches are held across certain chord changes, lower versions of previous pitches must be used in order to maintain just tuning. Though most nonkeyboard acoustic instruments, the brasses in this case, can vary the tuning of each pitch somewhat, most cannot match the degree of drift that occurs in the Gabrieli (‘‘A’’ begins the piece at 440 Hz and ends it at ∼398 Hz!). For players of these instruments a compromise between physical tuning limitations and the ideal of just intonation must be made. Players use just intervals wherever possible, until the pitch drift forces a decision as to where the ‘‘rub’’ will be. The pitch-drift phenomenon will be demonstrated.