Surface Tension (2015)

Composer Note:

Inspired by the way various indigenous drums (such as the Irish bodhrán or Middle Eastern frame drums like the Turkish Tar) play with the tension of the skin in order to bend the pitch to produce something almost approaching melody, I sought a way of making so-called unpitched drums “sing” in their own way in this piece. I was particularly interested in creating a kind of mobile pitch-space that shifted in and out of various overtone-based tonalities. This is a tall order for drums, instruments that are normally considered unpitched! But I liked the tension implicit in this possible scenario – it triggered my imagination. Actually realizing this strange idea took some work though, and I am deeply indebted to Third Coast for their assistance, and their spirit of complicit adventure and experimentation. I knew that I wanted the drums to move continuously through the pitch space, as in a pulsing glissando (something that crops up quite a bit in my music) and I was very happy when we discovered that you could change the tension of the drumheads of tom-tom drums by attaching plastic tubing into a hole on the side and blowing into the drum to tighten the skin of the head, thus raising the pitch. This alternate tightening and slackening of the drumheads of the toms became the modus operandi of the piece – by using this method I was able to gradually build pitch centres and travel between them. Some of these pitch centres are even overtone based – the players must gliss to very specific partials such as the 7th, 11th or 13th of a fundamental so as to create a strong resonant, fusing harmony. Essential in this quest is the addition of very precisely tuned bongos and travel congas. Of course, the spectra produced by all these drum instruments are rather strange, not really following the pattern of more standard pitched instruments, so even when all the drums are pulsing around a particular pattern of harmonics, one still hears many inharmonic things that create frictions in the way we perceive the pitch material. I find these frictions very interesting, and I sometimes play with them. As the drums start to go a little out of tune from the continuous tightening and slackening of their heads, I have also written “tuning zones” into the composition, where the players gently tune their drums in a rhythmic way using their normal technique of turning the tuning pegs.

—Donnacha Dennehy