27 The definitions of LA10, LA1 and LAmax are provided in the Noise Regulations. Briefly, these are measurements of the level of noise in decibels. "LA" refers to the level of noise in decibels ("dB") using the "A" frequencyweighting characteristic, which is a measuring system set out in the relevant Australian Standard. The number refers to the percentage of the representative test period beyond which the assigned noise level must not be exceeded. For example, where the LA10 standard is 45dB, this means that the level of noise must not exceed 45dB for more than 10 per cent of the time.
28 An influencing factor is added in circumstances where the land being tested is close to activities or uses, such as heavy industry, mining or roads, which increase the level of noise generally. Where land is close to such uses or activities, an influencing factor, calculated in dBs would be added to the standards set out in r 8.
29 It is clear from the evidence provided by both parties, that the modelling of noise is an inexact science. The results will depend upon how long the representative test period is, whether an influencing factor is assigned, and the quality of the data set used to underpin the modelling. It will depend upon whether a value is added to take into account the tonality, modulation or impulsiveness of the noise. It will also depend upon where, within the noise receiving property, the measurement of noise is taken.
30 Mr Nicolo Della Gatta gave evidence on behalf of the applicant. Mr Della Gatta is an acoustic engineer, with over 20 years experience, and with particular previous experience in measuring noise from child care centres. In modelling the predicted noise levels from the child care centre, Mr Della Gatta calculated the noise over a 4 hour period, which is the maximum test period which may be used under the Noise Regulations. In addition, Mr Della Gatta has not used the LAmax and LA1 measurements, and has instead based his report on the LA10 levels, calculated at 10m, with 12 children. His reason for doing so is because it his view that the LAmax and LA1 levels are not indicative of the noise.
31 Mr Della Gatta did not provide a quantitative analysis of the noise levels of children playing in his report which was tendered with his witness statement. He did however, provide anecdotal information regarding the likely noise output of particular groups of children. Because Mr Della Gatta did not model LAmax or LA1 levels, his report does not include information regarding the noise associated with the car park.
32 Mr Paul Keswick, a similarly experienced acoustic engineer with bachelor and PhD qualifications, gave acoustical analysis evidence for the Respondent. Mr Keswick was critical of Mr Della Gatta's method of modelling. It was Mr Keswick's opinion that the representative test sample should be 15 minutes during an hour in which the children are playing, rather than choosing a 4 hour period, within which children only play for an hour, as this artificially lowers the average noise level. Mr Keswick was also critical of Mr Della Gatta's decision not to include the LAmax and LA1 measurements. As Mr Keswick noted in the report appended to his witness statement: