What is "snickometer"

A Snickometer, commonly known as Snicko, is used in televising cricket to graphically analyse sound and video, and show whether a fine noise, or snick, occurs as ball passes bat. It was invented by English computer scientist Allan Plaskett in the mid-1990s. The snickometer was introduced by Channel 4 in the UK, who also introduced the Hawk-Eye and the Red Zone, in 1999.