Cochlea Unwound is a proposal for a permanent sound installation at Diglis Weir in Worcester. Like Organ of Corti, Cochlea Unwound uses the innovative acoustic technology of sonic crystals to recycle the noise of the weir into constantly shifting patterns of sound.
Cochlea Unwound (2010- ) Latest
Cochlea Unwound is one of the outcomes of our Wellcome Trust funded Tranquillity is a State of Mind project, which we developed in partnership with Sustrans, the sustainable transport charity. On that project we brought together a cognitive neuroscientist, a clinical audiologist and two acousticians to explore the relationship between sound, health and wellbeing.
Diglis weir is a constant source of noise in the landscape and acts as an effective mask to all other sounds occurring in the vicinity. In previous projects, such as the Warwick Bar Masterplan, we had explored the use of running water as a means to mask unwanted noise and we were interested in the capacity the weir has to effectively ‘tranquilise’ its surroundings, acting like J.G Ballard’s Sound Sweep; mopping up the surrounding sounds. We wondered if it might be possible to ‘sweep the sweeper’, neutralising the sound of the weir - a sound source often associated with tranquility - in order to make way for the other, indigenous sounds of the meadows near by. The precursor to Cochlea Unwound then, was for an installation we called The Tranquiliser (see video):
- As the cyclist or walker travels towards the weir, the amplitude of the dense, broadband noise increases. The route takes the traveler through The Tranquiliser, as they move closer to the weir. As they move through the space of The Tranquiliser, the sound of the environment is filtered so that the frequency (pitch) and the amplitude (loudness) decreases, until at one point, all sound is removed. The experience will be uncanny, as the walker will see the weir close by, but the sound will have been ‘turned off’, as though it has been sucked out of the environment.
While we were working with Seb Jouan from Arup on possible solutions for doing what we wanted to do with The Tranquiliser, we came across the technology of sonic crystals. The term ‘sonic crystal’ describes the use of a periodic array of spheres or cylinders arranged in such a way as to alter the path of a sound wave and in so doing, cause a noticeable attenuation of a band of frequencies in the audio spectrum. Like Organ of Corti, Cochlea Unwound will utilise this principle, tuning the incoming noise of the weir and sculpting it into continuously shifting patterns of sound, according to the proximity of the listener to the device.
Like Organ of Corti, Cochlea Unwound takes its name from the inner ear and alludes to the audiological process of ‘tonotopic mapping’, a term which describes the process by which sound is physically mapped according to its frequency content along the length of the basilar membrane in the inner ear. We became fascinated by the fact that like so many organisms, our auditory system is predicated on the physical separation of sound into space and we began to explore ways of representing this on an architectural scale.
Our proposal for the Cochlea Unwound provides a frame through which to listen to the tonotopic structure of sounds in the landscape by making audible the frequency bands within the sound of the weir. It uses the acoustic principles of a sonic crystal array to focus particular frequency bands within the weir noise. The array is made up of 8 sections each 900mm away from the previous section. Each section consists of 2 sets of a sonic crystal based on a theoretical ‘sonic lens’ design by Hakansson and Sanchez-Dehesa from Valencia Polytechnic. At the focal point of the first section, all frequencies between 1 and 2 kHz are enhanced while all frequencies between 2 and 3.2 kHz are attenuated. The focal point is quite small since a movement of only 30cm either side of the focal point will produce more than 10dB change between 1 and 2 kHz. Each consecutive section of the array affects a lower frequency band.
Following the completion of the Tranquillity is a State of Mind project, Cochlea Unwound is now in its second phase of development. During this phase of the project, we are developing the idea from a concept to a detailed design. As part of this process, we are working with artist Rob Colbourne, who is developing a methodology for a site analysis by means a project called Twenty Feet to an Inch, where he invites community groups to contribute to an in-depth study of the Western bank of the River Severn. We will also be bringing Organ of Corti to the site for 3 days during the Worcester Music Festival and undertaking a sound walk based on the Diagnosing the Sound of the Landscape sound cycle-ride.