Magnetic Resonance Imaging (MRI) procedures are increasingly common all
around the world, with more than 10,000 machines in service, performing over
30,000,000 scans each year.
MRI procedures are believed by virtually all authorities to be one of the
safest medical scanning techniques in use, however, MRI procedures can be scary
and uncomfortable due to the necessity for the patient to spend considerable
time inside a small space. Add to the claustrophobia-inducing chamber, the
extreme noise produced by MRI machines and many patients find the procedure
quite unpleasant, if not downright terrifying.
There is nothing one can do about the size of the chamber, or the need to
spend the required time inside to get the scan results needed by your doctor,
but we can help protect you from the noise.
How bad is the noise in an MRI and what level of protection
is recommended?
NOTE: Even with no hearing protection, most patients will not suffer
permanent hearing damage during a typical MRI procedure, so do not be alarmed by
the following analysis.
Noise levels inside an MRI machine during a scan typically vary from 65 to 95
dB, with intermittent spikes of noise as loud as 110 decibels, about the level
produced by a rock concert.
OSHA, the US government agency charged with enforcing workplace safety,
mandates that hearing protection devices be provided to workers any time the
ambient noise level in the workplace exceeds 90 dB, and requires that any
hearing protection devices provided reduce the noise in the ear to 85 dB or
lower. Since MRI machines produce up to 110 dB of noise, to meet the OSHA
standard of reducing the noise at the ear to 85 db or less, would require an NRR
rating of 25 or better (110 - 85 = 25).
The foregoing is a very conservative analysis. Hearing damage from an MRI
procedure is highly unlikely, even without any hearing protection. The primary
reason for using hearing protection in MRI procedures is to make the patient as
comfortable as possible so you can lie still letting the machine get the very
best scan of which it is capable. Your physician needs the clearest and most
accurate data she can get to guide her treatment decisions. So it makes sense to
make sure you have adequate hearing protection during your MRI scan procedure.
This is especially true of very young patients who are likely to be very
frightened.
What hearing protectors meet an NRR 25 level of protection?
Most disposable foam ear plugs offer an NRR 25 or better level of protection,
and virtually all MRI technicians will provide you with disposable foam ear
plugs when you arrive at the facility for your MRI procedure. For those who have
not had a lot of experience in using foam earplugs, however, these can be
difficult to use as well as very uncomfortable. For young children, foam
earplugs are not generally recommended.
A much better choice for hearing protection in an MRI procedure, is an ear
muff that is rated
MR Safe. Products with the MR Safe designation are certified by their
manufacturers to be free of metal so that they will neither react to the extreme
magnetic fields, nor will they conduct induced electrical currents that can
cause non-conforming products to become very hot during an MRI procedure.
An increasing number of MRI facilities have found that providing suitable
hearing protection ear muffs to their patients results in better scans from more
relaxed, less nervous patients. Ear muffs are simple to use, easy to adjust
so they fit properly, they are not as invasive as in-ear plugs, as well as being
more hygienic when suitable
protective ear muff covers are changed with each patient use.
Ear Plug Superstore offers an excellent selection of noise protection
ear muffs that are all certified by the manufacturers to be MR Safe. The highest
rated of these are the Pro-Ears MRI Safe Ear Muffs. The Pro-Ears Model 26 MRI
Safe Ear Muff is our top recommendation for use with children as young as 3 weeks old up to small adults.
For patients who suffer from noise sensitivities, commonly referred to as hyperacusis, dual protection is recommended. Dual protection consists of wearing
ear plugs under a set of ear muffs.
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