Little attention has been paid to the possibility of noise inducing hearing loss in divers, despite considerable evidence that divers suffer from occupationally induced deafness. Few measurements have been made of the noise generated by underwater tools. A set of measurements of underwater noise from five typical tools operated by a diver are presented. The levels were found in general to be very high and much in excess of those usually recorded for equivalent tools in air. Peak levels of up to 200 dB re 20 uPa were noted. The measurements were also analysed in the dB(W). unit suitable for underwater applications: levels were found that in the main were above the 85dB limit that in air would require action to be taken to reduce the noise. It was concluded that on the basis of the best criteria available, that two of the tools (an impact wrench and a Cox's bolt gun) were unacceptably noisy from a hearing preservation standpoint.


Industrial noise has progressively increased in Britain since the industrial revolution, and it has been estimated that about one million employees in the UK are exposed to hazardous noise levels in their workplace. Noise induced hearing loss is now the single biggest cause of industrial injury claims. Despite legislation requiring measures to conserve the hearing of employees, underwater noise exposure of divers has not received attention, despite considerable evidence from occupational audiology that divers suffer from deafness. While in part this may be ascribed to the exemption of offshore operations from the Noise at Work Regulations 1990, it is undoubtedly also due to the previous lack of a well established methodology for assessing the risk to hearing caused by underwater noise exposure.

The elements of a comprehensive hearing conservation programme are :

  1. To measure the noise levels to which the diver is exposed.

  2. To evaluate the hazard.

  3. To control the noise where necessary, for instance by the provision of hearing protectors.

  4. To monitor the hearing of all personnel exposed to high noise levels.

Of these, only the latter is currently implemented for divers. A step forward has been taken in the evaluation of hazard for the case of divers using SCUBA equipment or bandmasks by the provision by Al-Masri et al [l] of a scale which is appropriate for underwater applications. This scale, termed the dB(W), includes a frequency dependent factor that weights the noise to account for the changed sensitivity of the wetted ear, and hence allows the current in-air noise limits to be applied to the case of underwater exposure.

The purpose of this paper is to report some initial measurements of underwater tool noise, and to evaluate the hazard to hearing in the light of this approach.

Measurements of Noise Level

The methodology by which the noise levels of tools operated in air are measured for the purposes of assessing their hazard to hearing are well established, but no equivalent standard exists for underwater tool noise measurements.

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