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The evaluation of in-chamber sound levels during hyperbaric oxygen applications: Results of 41 centres.

INTRODUCTION
Noise has physical and psychological effects on humans. Recommended exposure limits are exceeded in many hospital settings; however, information about sound levels in hyperbaric oxygen treatment chambers is lacking. This study measured in-chamber sound levels during treatments in Turkish hyperbaric centres.


METHODS
Sound levels were measured using a sound level meter (decibel meter). All chambers were multiplace with similar dimensions and shapes. Eight measurements were performed in each of 41 chambers; three during compression, three during decompression, and two at treatment pressure, one during chamber ventilation (flushing) and one without ventilation. At each measurement a sound sample was collected for 25 seconds and A-weighted equivalent (LAeq) and C-weighted peak (LCpeak) levels were obtained. Recorded values were evaluated in relation to sound level limits in regulations.


RESULTS
The highest sound level measured in the study was 100.4 dB(A) at treatment pressure while ventilation was underway and the lowest was 40.5 dB(A) at treatment pressure without ventilation. Most centres had sound levels between 70 dB and 85 dB throughout the treatment. Ventilation caused significant augmentation of noise.


CONCLUSIONS
The chambers were generally safe in terms of noise exposure. Nevertheless, hyperbaric chambers can be very noisy environments so could pose a risk for noise-related health problems. Therefore, they should be equipped with appropriate noise control systems. Silencers are effective in reducing noise in chambers. Thus far, hyperbaric noise research has focused on chambers used for commercial diving. To our knowledge, this is the first study to investigate noise in hospital-based chambers during medical treatments.