Loud MRI Scanner
The loudest a scanner get may be about 110 dB, and is regularly above 85 dB. 110 dB is actually the discomfort threshold. The duration of exposure is one of the most important physical factors that determines the effect of noise on hearing. It should be noted that the acoustic noise levels suggested for patients exposed during MR procedures on an infrequent and short-term temporal basis are considered to be highly conservative. The MHRA's guidelines recommend that patients use hearing protection whenever the noise level rises to 85 dB or above. Ear defenders or earplugs afford approximately 20 to 25 dB reduction in noise. MagNET are have published acoustic noise measurements in their "bluecover" reports.