Third Umpire and Technology in Cricket: DRS, Hawk-Eye and Snickometer

What Is the Third Umpire?

The third umpire is an off-field official who monitors television replays and assists the two on-field umpires in making decisions that require slow-motion review — run-outs, stumpings, boundary calls (whether the ball cleared or touched the rope), catches (whether the fielder carried the ball over the boundary), and, in DRS-equipped matches, LBW and caught-behind decisions. The third umpire communicates with on-field umpires via earpiece and relays the decision back to the ground.

The Decision Review System (DRS)

DRS is a framework within which players may challenge an on-field umpiring decision. Each team typically has two reviews per innings in Test cricket (one in ODI, one in T20I). A review is taken when the fielding captain or batting batter signals to the umpire. The review is then adjudicated using multiple technological inputs. A retained review (one not lost) means the player's challenge was upheld; a lost review means the on-field decision stood. Teams lose a review when their challenge fails.

Hawk-Eye Ball Tracking

Hawk-Eye uses six or more high-speed cameras triangulated around the ground to track the ball's trajectory from release to the point of impact with the batter's pad. The system models the rest of the ball's path as a computer projection — where the ball would have gone if the batter's leg were not in the way. This projection is used to adjudicate LBW dismissals: if the projection shows the ball hitting the stumps (outside the Umpire's Call tolerance), the batter is given out.

UltraEdge and Snickometer

UltraEdge (and its predecessor Snickometer) uses a microphone embedded in the stumps or on a stump-mounted device to detect tiny audio spikes at the moment the ball passes the bat's edge. These audio waveforms are synchronised with ball-tracking video to determine whether there was an edge onto the bat. If a significant audio spike coincides exactly with ball-bat proximity, an edge is confirmed — useful for caught-behind and LBW reviews where the bowler claims the ball hit the pad without hitting the bat.

Hot Spot

Hot Spot is an infrared imaging system that detects friction heat — where two objects have rubbed together. When the ball brushes the bat edge, gloves, or pads, it leaves a heat signature. Hot Spot cameras provide visual evidence of contact points invisible to the naked eye. However, Hot Spot is expensive and not universally deployed, and can miss very faint edges. Some broadcasters use it as supplementary evidence alongside UltraEdge rather than as a primary decision tool.