There is method in the madness: this live mix of "Descent" comes with an essay to perhaps contextualise things
http://soundcloud.com/senster/02-descent
Software, subharmonics and The Birds: some context on the creation of "Descent"
The sounds we hear in the natural world are usually made-up of a combination of notes each with a different pitch; each fundamental has various overtones above it, these are often called harmonics. Subharmonic sounds are produced by
undertones -- fractions of the fundamental tone produced by dividing the frequency of the fundamental "undertones”. What is interesting to me as a sound artist working predominantly with field recordings is that subharmonic sounds do not (as far as I am aware) exist in nature and have a strange, etherial, unreal quality to them, affecting the listener profoundly and in sometimes unpredictable ways.
Of notable mention here is Oskar Sala who famously wrote the soundtrack to Alfred Hitchcock's movie
The Birds which used an instrument called a
Mixturtrautonium. Originally devised in the 1930s, it predated Moog's electronic synthesizers by almost a decade and was developed to produce many of the expressive, warm sounds of the films of the 1940s and 1950s. Unlike a synthesizer (which would later become a more general-purpose tool), Sala's Mixturtrautonium was built to
specifically produce sounds in the subharmonic region. Nobody since mastered or played Sala’s instrument and when he died some years ago, it seemed that this particular branch of subharmonics was lost.
Few synthesizers were built that sought to recreate and integrate Sala's ideas into instruments; audio effects companies like Dolby produced various subharmonic processors, but their scope was vastly simplified and their utility reduced dramatically. Subharmonic synthesizers found applications in extending bandwidth limited analogue telephone systems -- thus the whole notion of using subharmonics as a tool for creative expression was relegated to the engineer's toolchest as simply another EQ device; thus it remained largely overlooked as sound designers explored other avenues of synthesis...
That was until 2000 when an interesting rediscovery of an East German instrument called the
Subharchordia. Originally developed in East Germany in 1960 at the “
Labor für Akustisch-Musikalische Grenzprobleme” (Laboratory for Problems at the Acoustics and Music Interface) its rediscovery resulted in a renewed interest in the sound of fractionally-divided fundamental tones.
Despite their differences both the Mixturtrautonium and Subharchordia were large, complex analogue devices which required a great deal of (usually analogue) electronics to produce sound. Modern computer DSPs can model subharmonics very easily and indeed have found many applications in engineering and throughout the scientific research community. However, returning to audio applications, subharmonics produced on a moderately powerful laptop can be easily achieved in real-time using relatively inexpensive computer hardware using both commercial and self-written software in max/msp.
Methodology: Malfunction://ouroboros and the "Descent" phase
I started working with subharmonics for the
Descent phase of my environmentalogue composition cycle
malfunction://ouroboros. I wanted a great many deeply resonant cavernous sounds in this movement to evoke an empty and wrecked civilization. I wanted specifically an environment that listeners would instinctively feel was alien. For this application I chose to explore the mysterious world of subharmonics to produce a very real and visceral response in the audience. To achieve this I started with a simple waveform (in my case a basic sine wave) to which I added subharmonic oscillator software called “
The Edge” (downloadable from http://www.codeaudio.com) to the send feed.
The resultant audio produced are true subharmonic frequencies, which meant they were lower than the fundamental frequency of the input signal to a ratio of 1/x. So, let's say I introduced an input signal with a fundamental frequency of 440Hz, the subharmonics produced included 220 Hz (half), 110 Hz (quarter), and so on. I further added to the effect and thickened up the sound by resampling the send feed using note replication using Supercollider -- reintegrating the sounds produced back into the return feed and mixed independently but with variable second-long delays producing an "overlap". Supercollider further layered the subharmonic oscillator's output which was adding lower frequencies in tune with the input signal.
After that I added a little echo to the individual voices so that the higher overtones had shorter decay and lower subharmonics had longer decay presence to produce the kind of time-smear one finds naturally occurring from multiple reflection points in a cavern.
The percussive beat was a recording from a train running over the tracks of Putney bridge, fed its own, fixed subharmonic process much as one would use a dolby dbx processor. Only the train sample was processed leaving the echo resonance unaltered so as to cut through the top-end of the soundfield.
To simplify the process for my live performance work I inserted a resonance filter because with the filter frequency and resonance I can more accurately pinpoint common areas that I'd like to subharmonically enhance. I also added a little compression/gate so as to not overload the PA and keep volume under control and I stretched the attack and release settings (I found sub bass is very susceptible to clicks and pops when there are sudden changes in amplitude). To ensure I was controlling the summed amplitude I placed a limiter directly after the laptop's stereo send so as to hold everything around -6dB (and not completely kill the PA) and hand-tweaked the limiter when things started getting dense or raucous.
The end result was as startling to me as I think the audience found. With a simple sinewave generator I was able to produce a yawning cavernous soundscape complete with rumbling and echo-filled chasms -- all of a sudden the composition developed a massive presence in the sub range and produced a thick resonant quality I would find hard to create live using conventional methods.
I'm hoping more people rediscover the qualities and nuances produced by injecting subharmonics creatively into their compositions; it already has many applications in foley and cinema sound design (where it is often used to "thicken up" and add presence to sounds for dramatic effect) but as a tool for creative expression, I believe it has many applications that musicians, sound designers and sonic artists have yet to rediscover and develop. The "Descent" phase is an illustration of what I was able to achieve using a laptop subharmonic processor as a performance tool to produce an end result I found interesting.