Sounds from memory #1: The MRI Scan
November 19, 2007
The intention of these series of posts is to document sounds that have remained in memory. Not sounds that are particularly pleasant or trigger ‘Proustian Resonance’ but unique sounds that once heard are never forgotten (therefore impossible to reproduce or record). If i get enough – and please add your own – i’ll organise them into a top ten ‘mnemaudio’ chart.
The MRI Scan
Andy (Wilson) and I regularly cite the MRI scanning machine as a prime influence on sunseastar’s music having both been fortunate enough to witness the machines unique timbre up close (…are sunseastar the only group where all members have had brain scan?). The Magnetic Resonance Image Scanner is a medical device used to generate images of the soft tissues of the brain for the diagnosis of illnesses. The unfortunate patient is strapped to a horizontal bed which is introduced slowly into the small cavity of a large metal wheel – a very claustrophobic and alarming experience – you are allowed a view of your feet via a mirror near your head but apart from that you can see nothing. The staff switch the machine on and leave the room with unsettling haste.
The sounds come in a series of about six sequences ( different angles of the scanning device through the head?) of a few minutes each over a total of thirty minutes (in my case). The noise is very impressive due to it’s volume and unexpectedness – It’s very loud and very close and, because you are strapped in to a small space, there’s no way to get away from it:
“Due to the construction of MRI scanners, they are potentially unpleasant to lie in. The part of the body being imaged needs to lie at the center of the magnet (which is often a long, narrow tube). Because scan times may be long (perhaps one hour), people with even mild claustrophobia are often unable to tolerate an MRI scan without management.”
The noise can be described as a high volume grating mechanical ‘GRRRR’ of regular but varying tone on each pass. If this sound came from any other machine it would be an indication that it was about to fail with catastrophic and lethal effect – which is quite alarming considering it is inches from your unprotected face:
“Acoustic noise: Loud noises and vibrations are produced by forces resulting from rapidly switched magnetic gradients interacting with the main magnetic field, in turn causing minute expansions and contractions of the coil itself. This is most marked with high-field machines and rapid-imaging techniques in which sound intensity can reach 130 dB – equivalent to a jet engine at take-off.”