Infrasound Acoustic Measurement System And Noise-based Study

In the natural and human's life, there are all kinds of sound, which can bedivided into three parts: infrasound, audible sound and ultrasound according tothe frequency of sound waves. The frequency range of infrasound is below20Hz, audible sound is from20Hz to20000Hz, and ultrasound is greater than20000Hz.The paper is do some research on the noise of audible sound andinfrasound. The desired signals are acquired by building acoustic sensormonitoring systems, which is mainly composed of the acoustic sensor, thedigital network transmission instrument and network server. The system canacquire sound signal of different frequency by replacing acoustic sensor. Thenthe collected data is uploaded to the network server where specified file folderbelow through the cable network or wireless network. Researchers can makeuse of this acoustic data to conduct signal analysis and processing.The infrasound has characteristics of low frequency, long transmissiondistance, and small energy attenuation and so on. In order to explore thecorrelation between infrasound and certain natural event, and to detect itsoccurrence mechanism and propagation rule, based on the wide area sensornetwork infrasound monitoring system has increasingly become the focus ofstudy.Through building the wide area infrasound monitoring network, the paperhas completed the collection of infrasound, analyzing and processing theinfrasonic signal, and further exploring propagation rule of the infrasonic wave.Five infrasonic signals are detected by five infrasound monitoring station inBeijing which is produced in an earthquake of Beijing four days ago. The signalis analyzed in time domain, frequency and correlation. It provided theoreticalbasis and practical support for the earthquake prediction and prevention, andwas conducive to the further understanding of earthquake occurrence.As a sound wave of human audible sound, noise, especially the cityenvironmental noise, is disturbing people's normal work and life more and more seriously. In allusion to the city environmental noise, the paper detected theenvironmental noise in the fastigium of the morning and the evening and at thenight near Beijing Institute of acoustics, and mapped out three amplitude noisemap using the Matlab software platform for noise signal processing. The papereduced a conclusion: the noise in the fastigium is greater than nights, and thenoise close to North four ring road is more greater than in the Institute ofacoustics, which provides data support for reducing noise.