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Re: MRI recording

Oh yeah, Thanks! I will ask about turning off the lights in hope of a light show to go with the sounds :)


On Wed, Jun 20, 2012 at 12:53 PM, Kris Hartung <krispen.hartung@gmail.com> wrote:
Here are the source files for Project MRI:
I found some funny emails on the project, copied below for your entertainment:
“I just had a most exhilarating experience: my first MRI (on my lower back).  This was amazing. I laid down on a sliding table, and they pushed me into a sarcophagus like tube with mere inches around my entire body.  They put large headphones on my head, and then for the next 30 minutes I was eased into a seemingly euphoric and meditative state. What I heard were a series of interesting sounds...from jackhammer-like hammering, to buzzing or vibrating cycles, bizarre sci-fi industrial like sounds, and so on. It was delightful.  The MRI technician said it was a rarity for someone to actually enjoy that procedure.  At one point in time, I was in a half waking/dream state and was awoke by my leg twitching.  I could have stayed in there most of the day. And the amazing thing is that when I asked about the source of the sounds, he said they were not mechanically generated; rather, around my body, encased in metal, was a giant electrical coil surrounded by helium, chilled down to a cool minus 270 degrees.  The sounds were a result of changes they were making in the electrical current and the resulting vibrations to the machine. Unbelievable...not sure how all that produces an image of my back, however.
...anyway, I started thinking, I would love to have that 30 minutes captured on a digital recorder so that I could use it for looping or as an ambient backdrop to my more experimental looping.
Are there any MRI technicians on the list?”
”The machine I was encased in wasn't unbearable at all...in fact, with the
firearm shooting headphones (exactly this, in fact, but modified with the
plastic tube from the control room), the sound was perfect. Those firearm
headphones filter out a lot of high end, and what I heard with them on was
exquisite...no more or less louder than the volume that I use for listening
to music.  I wish I had turned the lights off in the dressing room when I
removed the pants they provided, however, because the static electricity was

In light of the question, where's the melody...I did discern tones, albeit
very constant and industry like. I concur with Edward's comments about it
sounding like a strange sci-fi moving. In fact, it sort of reminded me of
Forbidden Planet and the scene where they were taking a tour of that
monstrous facility under ground with all the automated machinery developed
by aliens.”


FYI: from http://ucdirc.ucdavis.edu/facilities/index.php (see excerpt below). This machine looks exactly like the one I was in. Article discusses audio capturing techniques.
This URL has a sound clip of the MRI scan: http://www.cis.rit.edu/htbooks/mri/chap-13/chap-13.htm
Direct Link to wav file: http://www.cis.rit.edu/htbooks/mri/chap-13/sounds/se-1.wav (it is only one of many of the sounds...probably the most uninspiring in my opinion).  There must be more of these on the web somewhere.

Auditory System: Auditory stimuli are presented during scanning via a high-fidelity system designed for the MR environment (MR confon GmbH, 39118 Magdeburg, Germany). The headphones contain electrostatic transducers for a broad, flat frequency response and construction-grade Peltor earmuffs for passive damping of gradient noise. By using electrostatic rather than pneumatic transduction, this system produces sound quality comparable to a home stereo, with 88dB signal-to-noise ratio (SNR) and high channel separation. During a functional MRI scanning session, sounds can be presented at detection-threshold levels between "sparse" acquisitions or at conversational levels (approx. 75-80 dB) during continuous scanning. Active Noise Cancellation (ANC) in the headphones will further reduce the gradient noise and create a quieter environment for subjects. ANC is under final pre-release testing at MR-Confon, and the UC Davis IRC will be one of the first centers to use ANC in fMRI research. For communication from the subject, the subject's voice is transmitted to the scan operator via Phone-OR, an MR-compatible, optical microphone mounted on the headphones (Magmedix, Inc., Fitchburg, MA, 01420). This microphone system suppresses gradient noise from the transmitted audio signal, using both simple subtraction and advanced algorithms based on speech-recognition. Combined with the MR confon system, extremely clear bidirectional (subject to/from operator) communication is possible during scanning to provide excellent audio SNR for voice-key applications.