Anatomy of a Mountain Stream: quadraphonic fixed media, binaural version.
Field recording & processing programming: Edward Wright
We often take things for granted until we look carefully at them. During the cold snap of the winter of 2011 when the snow had dampened all the sounds I bravely/foolishly balanced a surround sound recorder on a rock in the middle of the stream that runs down from the Carneddau, through Parc Plas Mawr in Penmaenan on its way to the sea.
Through manipulating the playback speed of the resulting sound-file it was possible to expose many details of the sound that are often obscured by our ‘normal’ way of listening. By simply changing the sampling rate, we can enter what feel like different sonic dimensions where the very large, and minutely small sonic structures become far more apparent.
Effectively this means that I have slowed down and sped up the audio. More precisely a computer or CD player reads through audio in a number of steps much like you would go through pages in a flick book but a lot faster (CD reads at 44100 ‘steps’ per second).
All that I have changed is how quickly those steps are taken. What this does is to not only change the pitch of the audio as the sound waves become compressed or stretched out, but also to chance the perception of events. Things that seem a blur become a series of discrete happenings and events that seemed slow and random start to show striking regularity when viewed over a longer (or more compressed) time frame.
In this piece the original 8 minute sound-file is played in its entirety, but the speed has been mapped and composed to create the framework of the piece. The audio was recorded on a Zoom H2 at 4chan x 48kHz x 24 bit, processed in Max/MSP 5.
This version of the work had been mixed to give an approximation of the quadraphonic set-up of the speakers (i.e. 2 in-front and 2 behind) on headphones.
This has been achieved by playing a sound impulse from each speaker and measuring how it gets to a listeners ears. A sound from the extreme left will take slightly longer to reach the right ear than it takes to get to the closer left ear. Also the journey that the sound waves have to take around the head will absorb some of the energy, although not evenly across all pitches, changing fractionally changing the tone of the sound by the time it reaches the further ear.
Image from http://www.cns.nyu.edu/~david/courses/perception/lecturenotes/localization
If you played a sound from the right front speaker (for instance) and recorded that sound from microphones placed in the ears of a listener you can compare the signal from the speaker with those that have arrived at the ears. From this point we can work out what the change is and can also apply that change to any other sound.
This has been scaled up to the 4 separate audio channels and processed (impulse convolved) with the spatial data collected from the in ear microphones hence why you need to listen on headphones to get the full effect
SO, PLEASE ONLY LISTEN ON HEADPHONES NOT ON LOUDSPEAKERS!