Stump microphone

It was originally developed by Kerry Packer for World Series Cricket in the 1970s.

[1] At first it was primarily for entertainment value: "television audiences could hear the rattle of stumps".

[2] Later, the technology became part of the Decision Review System; the microphone detects the sound of a batter hitting the ball in order to determine whether they should be given out caught (or alternatively, not out leg before wicket).

[4] Conversely, England cricketer Moeen Ali suggests stump mics should be turned up, in order to deter players from sledging.

[5] As of 2019, International Cricket Council guidelines say the volume of the stump microphones must be turned down when the ball is dead or not in play.