Wambo Coal AEMR 2010-2011 - Peabody Energy

1.3 TerminologySome definitions of terminology, which may be used in this report, are provided in Table 1.2.Table 1.2 TERMINOLOGYDescriptorL AL A10DefinitionThe A-weighted root mean squared (RMS) noise level at any instantThe noise level which is exceeded for 10 per cent of the time, which isapproximately the average of the maximum noise levelsL A90The level exceeded for 90 per cent of the time, which is approximately theaverage of the minimum noise levels. The L A90 level is often referred to asthe “background” noise level and is commonly used to determine noisecriteria for assessment purposesL AeqL pkdB(A)The average noise energy during a measurement periodThe unweighted peak noise level at any instantNoise level measurement units are decibels (dB). The “A” weighting scaleis used to describe human response to noiseSPLSound pressure level (SPL), fluctuations in pressure measured as 10 times alogarithmic scale, the reference pressure being 20 micropascalsSELSound exposure level (SEL), the A-weighted noise energy during ameasurement period normalised to one secondHertz (Hz)Cycles per second, the frequency of fluctuations in pressure, sound isusually a combination of many frequencies togetherABLAssessment background level (ABL), the 10th percentile background noiselevel for a single period (day, evening or night) of a 24 hour monitoringperiodRBLRating background level (RBL), the background noise level for a period(day, evening or night) determined from ABL dataDayEveningNightThis is the period 7:00am to 6:00pmThis is the period 6:00pm to 10:00pmThe period 10:00pm to 7:00am11263_R01.docPage 4