How to detect the size of the noise around?

Can be detected with the function of the smartphone, simple and convenient, the detection method is as follows:

1, click the cell phone system application options;

2, and then find the toolbox options;

3, in the pop-up window prompted to select OK;

4, find the decibel meter tool;

5, at this time you can detect the size of the decibel meter in your room decibel size up, the noise level is the decibel meter.