Passive systems that use foam or other sound-deadening materials are insufficient to combat the noise. So the team attempted to solve the problem using existing air phones, or headphones attached to small tubes, connected via the tubes to specially crafted electronics and software located outside the MRI machine.
The air phones, which are similar to the headphones once distributed on commercial airplanes, pipe the sound via two tubes to tiny microphones connected to an amplifier and a signal processor several feet away.
That processor taps an algorithm, or set of computer instructions, to produce a sound signal that is the opposite of the signal just received. That opposite signal then gets piped back through a third tube to each of the patients ears.
Because the MRI sounds are repetitive and the piped-in sounds are timed to occur on top of the repetitions, the result is that the patient hears the same sound as he or she would have without any intervention but at a lower volume.
Trials of the system using a loud beeping sound similar to some MRI noises showed it could reduce the noise by as much as 15 decibels. Ambient noise is about 60 decibels, with jet engines and other extremely loud noises reaching 120 decibels. The students were only able to reduce actual MRI sounds by about four decibels, but they said further tweaks of the system and algorithm are likely to improve that result.
The teams results are significant and make a difference, said Gijs Bosman, a professor of electrical and computer engineering and the teams faculty adviser. Based on experiments and further testing of the prototype, the team has come up with several recommendations for further improvements.
Sam Coons, a project manager with Invivo and the company engineer who wor
|Contact: Gijs Bosman|
University of Florida