Snickometre

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 is often used in a slow motion television replay by the third umpire to determine if the cricket ball touched the cricket bat on the way through to the wicketkeeper. The commentators will listen and view the shape of the recorded soundwave. If there is a sound of leather on willow, which is usually a short sharp sound in synchrony with the ball passing the bat, then the ball has touched the bat. Other sounds such as the ball hitting the batsman's pads, or the bat hitting the pitch, and so on, tend to have a fatter shape on the sound waveform.
If, in the umpire's opinion, this is the case, and the ball was a legal delivery that was caught before touching the ground, then the batsman is given out by the umpire. The umpire does not have the benefit of the Snickometer, and must instead rely on his senses of sight and hearing, as well as his judgement. When the Umpire DRS (Decision Review System) was introduced to Test Cricket, Snicko was not considered accurate enough, and so another edge detecting tool Hot Spot was used.
Channel 4 in the UK and Channel Nine of Australia, amongst others, have used it to help determine if the batsman was out or not.