[Revised March 12, 2019]. Experts now recommend MRI testing double hearing protection: earplugs plus earmuffs together. MRIs are high risk for hearing loss, tinnitus, and hyperacusis. Sometimes ENTs recommend an MRI (Magnetic Resonance Imaging) to help diagnose different conditions, including possible causes of hearing problems. MRIs use magnetism, radio waves and a computer to create images of hearing and/or balance structures. MRI can’t be done on people with pacemakers, metal chips, or metal implants in their body, because it interferes with the magnetism.
In 2018, scientists found noise levels of modern MRI machines are extremely high. MRI machines have average noise like a jackhammer or chainsaw loudness (110 to 115 dB), and peak or max noise as loud as gunfire (130 dB). International noise exposure limits recommend no more than 15 minutes of unprotected exposure to 100 dB. MRI tests usually take much longer than that. The stronger the magnetic field from the MRI machine, the higher the noise, and the higher the risk of hearing loss. This is a serious concern, especially for people who need more than one MRI over time.
Sometimes people are offered MRI safe—no metal—earplugs or earmuffs when getting an MRI done. Sometimes people bring their own MRI safe hearing protection. But earplugs or earmuffs are not enough for the high MRI noise. This is one of the rare situations where the general public must always protect their hearing with well fitted double hearing protection: foam earplugs plus high noise reduction earmuffs with the highest Noise Reduction Rating possible. See chapter on Hearing Protection for more details.
MRI departments should always provide double hearing protection, and have a variety of MRI safe earplugs and earmuffs to fit different shapes and sizes of ears including children, women and men. For some people with hyperacusis, noise during MRI testing will still be painful even with double hearing protection.
Newer more powerful MRI machines can have even higher noise levels (150 dB range), louder than military jets taking off from aircraft carriers. There is high risk of hearing loss, tinnitus, and hyperacusis, even when people use double hearing protection. Medical experts are asking MRI manufacturers to make quieter machines with much lower noise to prevent hearing system damage in people who need MRIs.
The tech is being developed. A March 11, 2019 article in Fast Company by Mark Wilson shared news that scientists have developed a shape that blocks all sound. A team at Boston University have developed an “acoustic metamaterial” that blocks sound. It still lets air and light through.
The possibilities are endless. Quieter MRI machines. No more noisy leaf blowers, vehicle exhausts, aircraft engines. Will be exciting to see where this research takes noise control.
[Photo Credit Ken Treloar at Unsplash]
Jan L. Mayes
Eric Hoffer Award winning author, audiologist, blogger, noise activist, bookworm, playing with words.