Sitting at my desk in the Annex at Bogong Centre for Sound Culture with the window in front of me open, as I type I hear the rush of water from the East Kiewa River below. It filters up through the trees, carried on a gentle breeze that brings with it the songs of local bird life. It's a familiar sound. One that, if I allow my mind to drift, could just as easily be that of the ocean, traffic or the roar of the city. In fact, as previous resident Michael Terren noted in one of his journal entries, in the fog of early morning I often mistake it for such sounds, which I know well from years of city living in the metropolitan hubs that dot the east coast of Australia.
This sound is called pink noise. It can be found regularly in both wild and constructed environments and there is even evidence that it occurs in the brain. It is distinguished from other kinds of noise by the balance of frequencies it contains. Other kinds of noise include red (or Brownian) noise, white noise, and even grey noise. Of these white noise is the most well known. Often called static it is the sound you get from an untuned analogue TV when all you can see on screen is black and white 'snow'. It is noticeably sharp to the ear and frequently considered offensive, or at least disruptive. Pink noise, meanwhile, is a much more diffuse sound, like that I hear out the window now. This is because of the frequencies it contains. White noise includes every frequency in the range potentially audible to human ears - 20 Hz (or cycles per second) to 20,000 Hz - at equal intensity, or power. That is, with each frequency having the same amount of energy as the others. Why then does it sound so abrasive and sharp? Because humans don't hear all frequencies equally, and this is where pink noise comes in.
Pink noise contains the same frequencies as white noise but at equal loudness per octave rather than equal power. Mathematically it is referred to as 1/f noise because the energy or power of the sound is inversely proportional to its frequency. This means that there is more power in the low frequencies - bass like you get from a sub-woofer in a car - than the high frequencies. However, as I mentioned people tend to hear pink noise as more balanced than white noise. This is because of the way humans hear. Instead of hearing all frequencies equally, human auditory systems emphasise certain frequencies over others. For example, people hear the 1 kHz to 4 kHz band in which most human speech falls particularly effectively. Indeed, as I discussed with Linda and Faye on Alpine Radio this week, this emphasise has translated to the frequency response of much audio technology, such as radio. Because of this, the increased low frequency content of pink noise helps to balance out the spectrum of noise as people hear it.
Gradually I have become fascinated with pink noise. For many reasons, I suppose. Living in the city but privileged to spend significant time in rural and regional areas, I enjoy the way this noise permeates seemingly all environments, at some level. There seems to be an ever increasing divide between urban and non-urban life around the world, and particularly in Australia. Across social, political and economic domains the built environments of cities are prioritised, at times at huge costs to environments and people elsewhere. Pink noise crosses this boundary, like so many others, linking the urban to the bush and the human to the non-human, articulating a connected whole of which all are part. Sounding at once like everything and nothing in particular, it emphasises listening and interpretation.
While here I will develop a new installation work using pink noise. Tentatively named 'The Flood', it will, as the name implies, produce a 'flood' of pink noise, like that which courses through Bogong Village and those that course through the streets, communication networks and homes of Australian cities. This first week has been filled with explorations and early experiments, along with nourishing meals and discussions shared with Madelynne and Mel. I'll share some more details of what I've been working on next time.