As I describe in Chapter 3 of Between Air and Electricity tuning forks are in some ways a kind of predecessors of microphones and loudspeakers. Furthermore they can be seen also as a predated sine tone generator. Tuning forks were extremely important for nineteenth century acoustic research. A tonometer, for example, was a large set of tuning forks and used to define the frequency of other sounds. The one depicted above was made by Rudolph Koenig and contains 670 tuning forks from 16 to 4096 Hertz. It was exhibited during the Philadelphia Exposition of 1876 and apparently regarded as being “the most scientifically important instrument at the event”. (see Smithsonian National Museum of American History).
Nowadays tuning forks have left the scientific realm, and even for tuning often a digital device is preferred. But now and then they become part of a musical performance. Oscar Bettison uses two sets of tuning forks, each forming a chromatic scale from C4 (261.63 Hz) to C5 (523.25) in Apart (2012) for four percussionists. Each percussionists has six or seven differently pitched tuning forks. Oscar mentioned to me, that he is fascinated by tuning forks, because “For me they are like this beautifully dumb instrument—each one only has one note, but it’s a “perfect” note!”
One of the aspects which turns these tuning forks in Apart into a musical instrument—and which interests me in particular of course—is the use of amplification. The sound normally only heard privately in a singer’s head to find the right pitch, is made public in the concert hall now. Also, this amplification clearly influenced the compositional process, when Oscar worked with Sō Percussion to develop this piece: “In the studio we were thinking of resonant surfaces [to amplify the tuning forks], but nothing was particularly amazing, so we thought we’d try contact mics. The first problem was that tuning forks buzz, so we covered the mic enough to get rid of the buzz, but for it still to amplify. I’d already written material for them to play, it was a kind of chorale, but then we started using the amplification and we realised that the mic was a playing surface—they could strike the tuning forks somewhere else and then place them on the surface slowly or really quite rapidly.”
A weird relationship between the visual and audible aspects of sound production is characteristically for Apart. The biggest gesture—a tuning fork being hit to bring it into vibration—is nearly silent, whereas the sound being heard is caused by the small gestures placing the tuning forks on the surface equipped with the contact microphone. Sonically, a weird organ sound is the result, often emphasised by two percussionists playing the same pitch. The tuning fork resonances are slowly getting softer and then interrupted by a soft click of the tuning fork being hit to vibrate it again. At the end of each section in the score (see the score fragment below), Oscar asks all percussionists “to strike the fork(s) they require for the next bar simultaneously” and this should be done “as a grand gesture”.
The ways of placing the tuning forks on the cloth covering the contact microphone are notated precisely in the score and are the main feature of the piece. For example:
– R.P. is the abbreviation for Regular Pulsing and indicates to “chose a tempo and pulse the tuning fork(s) on the playing surface”.
– I.P. is the abbreviation Irregular Pulsing and one has to “Pulse the tuning fork(s) irregularly on the playing surface ending with a sustained note”.
– I.A. is the abbreviation for Irregular Alternation and the percussionist should “Alternate two tuning forks in a polyrhythm”(from the performance instructions of the score of Apart by Oscar Bettison, Boosey and Hawkes).
These different kinds of pulsations move slowly from the highest to the lowest tuning forks during the composition. The soft clunks of the unamplified tuning forks—sounding when hit to bring them into vibration—are a beautiful counterpoint to the airy sounds, produced when the forks are amplified. You can listen here to a recording of the piece, performed by Sō Percussion: