A “noise map” has been developed by Shanghai Academy of Environmental Sciences which allows people to “see” noise. On this map, each street block and major road within the Outer Ring road is given a color. There are a total of 12 colors which represent 12 noise levels. For example, a purple color means noise detected in the certain area is between 30 and 35 decibels. Red color indicates 60-65 decibels and blue color is between 75 and 80 decibels, etc. Roads along busy elevated ways are often of red or blue color, while neighborhoods and parks are usually quieter, showing a color of green or purple.