Spectralism refers to a group of composers that study the acoustic properties of sound and incorporate what they learn into their compositional method. For the most part the IRCAM Centre in Paris is the nexus of the spectralist movement, hosting research, concerts, and education with a focus on contemporary French music and technology.
In music the term “spectrum” usually refers to an analysis of all the frequencies that are present in a sound signal. Every naturally occuring pitched sound has a layered pattern of frequencies called overtones. The number and relative strength of these overtones is a major factor in determining the timbre of different instruments – this is why a flute sounds different from a clarinet which sounds different from a trumpet and so on. As technology evolved it became possible to plot the spectrum of musical sounds in graphs that look like so:
That’s the first few notes of Debussy’s Syrinx for solo flute, plotted in a graph. Colors show intensity of sound at a given frequency, and you can see the layered overtones in the horizontal bands.
Sprectralists use the information garnered from computer analysis to make predictions on what a particular combination of instruments will sound like. Generally speaking, this music is about the manipulation of musical timbres – it tends to be somewhat slow and pensive, featuring lots of sustained chords with cool orchestrations. Sometimes the works involve computer generated sound, but one can also write a spectralist work with all acoustic instruments.
Gérard Grisey is one of the founding fathers of the spectral school. His Partiels, from 1975, has been cited as a major inspiration for the generation of composers that followed. Its main idea is based on a repeated low E, played by a trombone. Grisey analyzed a sample of this note and constructed combinations of winds and strings that could mimic and transform it. Thus there is a sense that the entire piece is a kind of X-ray and expansion of that one note.
Partiels is part of a larger cycle called Les espaces acoustiques. You can get the whole thing on Kairos records.
Marc-André Dalbavie is a spectralist who tends to write for purely acoustic ensembles. His knowledge of timbral principles results in music that is sonically adventurous but also super-smooth and elegant. Color from 2002 starts out spacey, like Partiels, but it is more conservative – I think you can hear familiar echoes of Debussy in there. Also, even on a first hearing there is a sense that we are going somewhere interesting – unlike many others in this day and age Dalbavie employs a relatively traditional large-scale rhetoric that is easy to follow.
You can get this on a somewhat hard-to-find CD. The whole thing is very enjoyable.
Lichtbogen from 1986 was composed right after a period of study at IRCAM, and Saariaho has described it as a celebration of her newfound abilities to manipulate sound. It uses some electronics (amplification with a lot of reverb) to make the ensemble sound much bigger than it is, but it is otherwise a pretty straightforward chamber piece.
It is available on this excellent and challenging album:
For a while, computers were not fast enough to make interesting music in real time. Pure computer music was painstakingly designed by engineer/composers, transferred to tape, and then simply played back from recording. The spectral composers, with all their computerized analysis of sound, were naturally very interested in making standalone computer pieces as well as tape-and-live-performance hybrids.
English composer Jonathan Harvey‘s Mortuos Plango, Vivos Voco from 1980 is considered another important referential work from the spectralist movement. It samples the bells of Winchester Cathedral, using this sound as the harmonic basis of the work. (Acousticians find bell tones particularly interesting because they are complex – they are not a neat and predictable stack of overtones like wind or string instruments.) Here’s a wikipedia article that provides more details – I think the most salient fact about the piece is that it is sonically very pleasant and dramatically exciting.
Sadly, this recording appears to be out of print. Here’s an Amazon listing of the CD.
Eventually computers became fast and powerful enough to make music in real time and even interact with a live performer. Many composers consider this to be the cutting edge of technology in music, and it is easy to understand why — with a dynamically interactive framework, a performance can take on the spontaneity, individuality, and nuance that we expect from classical music. The previous generation’s electronic music was, in comparison, “canned” – the electronic part would always sound exactly the same. Also, it is now possible to generate a massive conflagration of sound that is wholly derived from the live performer, making the piece seem more organic and less “fake.”
For me the gold standard of interactive electronics is Anthèmes II by Pierre Boulez. Boulez has been a highly influential composer since the 50s, of course, and he was a founder of IRCAM. It is difficult to say whether he is a spectralist, exactly, but his more recent work does sometimes display the timbral delicacy of his colleagues. (That would be a good research topic! “Spectralist Aspects of Recent Boulez”) But anyway, he was among the first composers to create these interactive electro-acoustic works.
This youtube clip shows a violinist playing the solo part for Anthèmes II (which is based on a preexisting piece with no electronics called Anthèmes) while the computer tracks what she is doing. At :30 we get the same performance with the computer’s output added into the mix.
Here’s a live performance which gives you even more of an idea of what the piece is like.
To really dig Athèmes II I think you need both the original, solo version and the electronically enhanced one. It really helps one appreciate how much the machine is doing (and how challenging this would be to design.) My solo version comes from this recording by Julie-Anne Derome.
…and the full version appears here, along with other great pieces by Boulez.
I want to finish with Saariaho’s hauntingly beautiful Lonh for soprano and electronics. This live excerpt shows how it is often presented with video as well. I believe in the beginning of this clip all the sounds you are hearing are derived from the singers voice – the drone is basically an extreme form of reverb, and the bird-like sounds are probably the results of filters that can pull certain frequencies out of the signal. Later (around 1:40) you can hear the contributions of pre-recorded percussion and voice parts in the mix. I had the pleasure of hearing this work in person last March, and it was probably the highlight of my whole season.
Live performance with Valérie Gabail.
Lonh has been recorded by the intrepid new-music soprano Dawn Upshaw. As I mentioned back in Installment II I’m a little tired of Dawn’s voice, but it is still a cool piece.
Some other figures who I shortchanged in this summary include Tristan Murail and Claude Vivier. Also, IRCAM and the Spectral school do not have an exclusive claim on interactive electronics – here in the states Morton Subotnick and many others are doing work in this area.