“The constituent elements in assessing the exposure of a person to noise which may be injurious are pressure level, frequency and duration. Pressure level or "loudness" is measured in decibels. Frequency is measured in hertz. The ear is more vulnerable to injury from noise which is transmitted on frequencies between 1kHz and 4kHz. Therefore noise meters attach more weight to noise which is received within this middle range of frequencies than to noise which is received on the less harmful higher and lower bands. A meter will thus produce an overall reading in what are called "A-weighted decibels" or "dB(A)." The concept of "leq" has to do with duration of exposure, and is the "notional sound level which, in the course of an eight-hour period, would cause the same A-weighted sound energy to be recorded as that due to the actual sound over the actual working day." The modern noise meter takes into account all these factors of noise pressure, frequency and duration, and translates them into a formula expressed as so many dB(A)leq.”
“Epidemiological studies in both this country and America have shown that if a population is exposed to noise at a level of 90dB(A) for eight hours a day, five days a week, 48 weeks a year for 30 to 35 years, it can be expected that 15 to 17% of that population will develop noise induced hearing impairment; if the exposure level is 85dB(A) for a similar period, the expected incidence of impairment is 6 to 8%.”
“It is now well established that the 'watershed' between risk and safety is defined at 90dB(A)leq. As we have seen above, it is known that prolonged exposure to noise in excess of 90dB is liable to result in hearing loss to the average person. In fact, some people are more vulnerable to noise than others. All human ears are not identical. A relatively small number of people may suffer injury from a noise dose of less than 90dB(A)leq. Others may have extra resilience; they may be able to cope with regular noise in excess of 90dB(A). However, the courts have held that 90dB(A)leq is the dividing line between risk and safety. If the worker (plaintiff) proves that the employer (defendant) exposed him to a 'noise dose' of 90dB(A)leq or higher, his claim will succeed. That is to say, the plaintiff must prove that he was exposed to the equivalent of noise in excess of 90 A-weighted decibels for 40 hours per week.”
“It is now well established that it is for the employer both to plead and to prove that it was not reasonably practicable to make and keep the working place safe… It is important that the employer should plead his case on this so that the employee can know and test the case he has to meet.”
“By setting the threshold at 85bB(A)leq in the claimant's case, the court is doing no more than saying that this is the level at which the risk of injury to him was foreseeable by the defendant...”
“From these authorities I deduce the principles that the overall test is still the conduct of the reasonable and prudent employer, taking positive thought for the safety of his workers in the light of what he knows or ought to know… [W]here there is developing knowledge, he must keep reasonably abreast of it and not be too slow to apply it; and where he has in fact greater than average knowledge of the risks, he may be thereby obliged to take more than the average or standard precautions. He must weigh up the risk in terms of the likelihood of injury occurring and the potential consequences if it does; and he must balance against this the probable effectiveness of the precautions that can be taken to meet it and the expense and inconvenience they involve. If he is found to have fallen below the standard to be properly expected of a reasonable and prudent employer in these respects, he is negligent.”
“Given the seriousness with which the noise problem was dealt with over the years, I infer that the matter was considered with a sense of responsibility and that there appeared to be adequate reasons for not adopting the precaution.”
“8 Ear protectors (1) Every employer shall ensure, so far as practicable, that when any of his employees is likely to be exposed to the first action level or above in circumstances where the daily noise exposure of that employee is likely to be less than 90d(B)(A), that employee is provided, at his request, with suitable and efficient personal ear protectors… 11 Provision of information to employees Every employer shall, in respect of any premises under his control, provide each of his employees who is likely to be exposed to the first action level or above… with adequate information, instruction and training on - (a) the risk of damage to that employee's hearing that such exposure may cause; (b) what steps the employee may take to minimise that risk; (c) the steps that that employee must take in order to obtain the personal ear protectors referred to in regulation 8(1)….”
“This raises the question, whether ear plugs or ear muffs could be used by a driver consistently with his safe operation of the train. The best which I can do on the evidence available is to conclude, on the basis of what was said both by the claimant and by Mr Smart, that this question must be answered in the negative.”