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Occupational Hearing Loss
Published in Ronald Scott, of Industrial Hygiene, 2018
Brief exposure to high sound levels can cause a ringing sensation and temporary threshold shift (temporary drop in hearing acuity). After a rest period the hearing returns to normal. If exposure to excessive sound is repeated frequently, there is a permanent threshold shift (loss in hearing becomes permanent). Hearing loss caused by noise is termed noise-induced permanent threshold shift. People vary greatly in their susceptibility to hearing damage by continuous sound exposure, but at high levels everyone loses some hearing ability. Workers exposed daily to high noise levels display the greatest loss during the first years. If we set the standard for serious hearing loss at a 25-dB or more drop in acuity, over a work lifetime of 40 years 18% exposed to 90 dB and 70% exposed to 115 dB incur such loss. Approximately 75% of the workforce are exposed to sound levels above 85 dB.
Instrumentation for Noise Measurement and Analysis
Published in David A. Bies, Colin H. Hansen, Engineering Noise Control, 2017
David A. Bies, Colin H. Hansen
Personal sound exposure meters are designed to be carried by individuals who are exposed to varying levels of high-intensity noise; thus they are small in size and simple to operate, with a microphone that can clip on to the lapel of a coat or shirt. Personal sound exposure meters are available to comply with European, Australian and American regulations. The meters complying with Australian and European regulations have the following characteristics: an eight-hour exposure to a level of 90 dB(A) constitutes a 100% daily noise dose; and for each 3 dB increase above 90 dB(A) the noise dose is doubled for the same exposure time. Some older personal sound exposure meters inhibit their energy integration below a level of 80 dB(A) and these should not be used as they are obsolete. In the USA a 5 dB weighting rather than the 3 dB weighting mentioned is used to determine exposure, and energy integration is inhibited below 80 dB(A). Some personal sound exposure meters also allow a 6 dB weighting (see discussion, Section 4.3). The upper limit for some personal sound exposure meters is 130 dB(A) but 140 dB(A) is more desirable, especially when the user is exposed to impact noise.
Disorders of Hearing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Linda M. Luxon, Ronald Hinchcliffe
The use of the term ‘level’, as in ‘sound pressure level’, indicates that a value is being expressed on a decibel scale. A value given as a ‘sound pressure’ would be in pascals. Similarly, sound energy values are stated in joules, sound exposure values are in pascal-squared seconds, and sound exposure levels are in decibels. The International Organization for Standardization (1997: ISO 10843) defines the peak sound pressure for any specified time interval as the maximum absolute value of the instantaneous sound pressure (expressed in pascals) that occurs during that specified time interval. The same standard defines peak sound pressure level as ten times the common logarithm of the square of the ratio of peak frequency weighted sound pressure to the reference sound pressure (expressed in decibels).
The hearing health of live-music sound engineers
Published in Archives of Environmental & Occupational Health, 2021
Siobhan McGinnity, Elizabeth Francis Beach, Robert S. C. Cowan, Johannes Mulder
Under workplace health and safety legislation, managing the risk of hearing injury for staff employed in music venues in Australia falls within the same legislative parameters for workers in other industries. This legislation limits sound exposure of an employee to 85 dB LAeq for an 8-hour work day without the need for provision of hearing protection or other hearing conservation measures. The “safe” exposure time is halved for any doubling of intensity (eg 88 dBA for 4 hours).20 However, these legislative criteria are based on research into the effects of continuous industrial noise exposure, and their application in the musical environment can be problematic, due to the variability of intensity and frequency that is a characteristic of all music.