AS 1055 pdf download

AS 1055 pdf download.Acoustics—Description and measurement of environmental noise
1 SCOPE
This Standard sets out general procedures for the description and measurement of environmental noise, including repetitive impulsive noise. It defines the basic quantities to be used for the description of noise in community environments and provides basic procedures for the determination of these quantities. The Standard applies primarily to noise emitted from industrial, commercial and residential premises. It excludes the setting of environmental noise criteria. Such levels are set by regulations or organizational policy. This Standard does not apply to the following: (a) The measurement or assessment of in-transit air, rail or water transportation or road transportation on public roads (which may be present in the ambient noise occurring at a location). (b) Noise that consists solely of discrete impulses such as those encountered in shooting and blasting. (c) Noise from wind farms. In this Standard, all sound pressure level descriptors are A-weighted, unless stated otherwise. NOTE: Guidelines for the application of this Standard are given in Appendix A. The structure of this Standard is as follows: (i) Definitions and symbols. (ii) Instrumentation. (iii) Measurements— (A) general locations, times, conditions and methods for general measurements; (B) methods for assessing specific environmental noise situations; (C) methods for setting objectives and specifications; and (D) methods for assessing conformance to objectives and specifications. (iv) Reporting and information to be recorded. (v) Appendices.
3 DEFINITIONS
For the purpose of this Standard, the definitions given in AS 1633 and those below apply. 3.1 Adjusted percent exceedance A-weighted sound pressure level (L A%,adj,T ) The A-weighted sound pressure level that is exceeded for the percent exceedance under consideration for the time interval considered, plus specified adjustments for tonal character and impulsiveness of sound. 3.2 Ambient sound The totally encompassing sound in a given situation at a given time, composed of sound from all sources near and far, measured by the totally encompassing time average A-weighted sound pressure level in a given situation at a given time. 3.3 A-weighted sound pressure (p A ) The root-mean-square (r.m.s.) sound pressure determined by use of frequency-weighting network ‘A’. NOTE: For the definition of A-weighting, refer to AS IEC 61672.1.3.9 Long-term average A-weighted background sound pressure level (L A90,LT ) The arithmetic average of the A-weighted background sound pressure levels (L A90,T ), after discarding any atypical results. NOTES: 1 One example of this is a long-term period average background sound level (L A90,period,LT ), where the period is either daytime, evening, or night-time. 2 Some regulatory authorities use L A95,LT for long-term average background sound pressure level.NOTE: In some cases, more than one long-term time average A-weighted sound pressure level will be of interest; for example, a long-term time average A-weighted sound pressure level obtained by averaging levels for the daytime reference time intervals and a long-term time average A-weighted sound pressure level obtained by averaging levels for the night-time reference time intervals.NOTE: In some cases more than one value of the long-term time average rating level will be of interest; for example, a value obtained by averaging the levels for daytime reference time intervals and another obtained by averaging those for night-time reference time intervals, over a period of several days, typically one week minimum. 3.13 Long-term time interval (LT) A measurement time interval (a period of 4 h or longer) for which the results of the noise measurement are representative of the situation under investigation. NOTE: The long-term time interval (LT) consists of a series of reference time intervals and is determined for the purpose of describing the environmental noise. It is generally designated by relevant authorities. It may also be related to a period of the 24-hour day, typically daytime, evening or night-time.