For the purpose of measuring environmental noise of urban area at any moment

a new kind of virtual environmental noise automatic measuring instrument has been developed based on the LabVIEW.This design is according to GB3096-2008 environmental quality standard for noise.The hardware system is based on sound pressure sensor and personal computer.With the application of the virtual instrument technology

high integration was realized for the functions of the traditional sound level meter by software.The layout of controls and indicator in front panel is rational.The measure range of this instrument is from 25 dB to138 dB

with the accuracy of ±1.5 dB and the resolution of 0.1 dB.Using the VI

it can be measured and noted that the ambient noise dB(A) level

the transient dB(A) level

equivalent continuous dB(A) level and the maximum and minimum dB(A) levels at any moment.The VI can real-time display the ambient noise signal waveform and frequency spectrum.At the same time it can give the alarm when the dB(A) level state exceeds standard automatically and recode the correlation data.