变电站噪声控制技术导则 DLT 1518-2016e.pdf

DL/T1518-20162012.For ease of use,some of the terms and definitions in GB/T 3947-1996 and HJ 2016-2012 are repeatedbelow.3.1 specific A-weighted sound level LAsA-weighted sound pressure level radiated from a fan per unit flow and pressure,LAs,the unit is dB(A)LAs=La-101g(H2Q)+19.8where LA is the A-weighted sound level of the fan,in A-weighted decibels,H is the total pressure of thefan,in Pascal,O is the volume flow rate of the fan,in cubic meters per minute3.2 sound shadow zonean area where sound waves fail to propagate owing to obstacles or refractionGB/T 3947-1996.definition 2.823.3 resonance frequencythe frequency at which the system resonates3.4 critical frequencythe lowest frequency at which the coincidence effect of the system occurs3.5 structure-borne noisethe noise induced by the mechanical vibration transmitted within building structuresGB/T 3947-1996,definition 12.63.6 reverberation timethe needed time that the sound energy flow density decays from original value to its one percent permillion(60 dB),when the sound is in steady state and then turns offGB/T 3947-1996.definition 12.473.7 sound absorption coefficientthe ratio of the sound energy of the incident sound wave absorbed by a material surface to the soundenergy of this wave on the surfaceHJ 2016-2012,definition 6.2.63.8 insertion lossthe sound pressure level difference at a specific location with and without sound insulation structure(muffler)during in-situ measurementsGB/T 3947-1996,definition 5.393.9 transmission lossthe sound pressure level difference between the incident noise and the noise passed through noise-insulation structure and muffler3.10 noise-sensitive buildingsbuildings need to keep quiet,such as hospitals,schools,govemment departments,scientific research2