Grunting affects opponent’s response time

Published in The Hindu on January 27, 2011

“Quiet please; thank you.”

There has been no tennis match, be it Grand Slam or Chennai Open, when the chair umpire has not mentioned these words several times during a match before a player serves. At times, players even wait for the spectators to take their seat before they serve, as was seen in a men’s singles match in the Australian Open now being played at Melbourne.

The reasons are simple: nothing should get in the way of the players’ concentration while playing.

After all, the ball is served at speeds even exceeding 200 km per hour (kmph), and the ball is hit by each player at nearly more than 125 kmph speed during the game, and the distance between the two players across the net is just a few metres.

So can grunting, shrieking and other noises made by the players themselves while playing affect the concentration of the opponents? Especially when the decibel level of the grunt is comparable to that of a lion’s roar? Maria Sharapova leads the pack of grunters with a decibel level of 101.

A preliminary study published in PLoS ONE journal shows that grunting affects the concentration of the opponent. So much so, that the opponent’s response time gets affected by a few milliseconds.

Judging the direction

Players are tuned to listen to the sound and time of the ball making contact with the racket, and this helps them judge the direction, spin, and velocity of the ball.

The study involved 33 undergraduate students from the University of British Columbia who had only recreational tennis experience.

These students were made to watch 384 video clips made of a professional tennis player hitting the ball (either forehand or backhand) to either the left or right of the video camera.

There shorts were edited in such a way that they showed forehand shots hit both crosscourt and down the line, and backhand shots hit both crosscourt and down the line. The clips were edited for sound as well.

Each video clip was played with or without accompanying sound. The researchers also edited for the length of the sound — those that ended immediately on contact or 100 milliseconds after the ball makes contact with the racket.

Since the decibel levels and the kind of noise made by players vary, the researchers used white noise at 60 decibel volume. 60 db is much lower than what is generally heard from the players during a match.

The results clearly showed the response time of the participants in the study was compromised when the clip was accompanied by sound.

The response time was also different when the white sound ended immediately after contact with the racket and when it prolonged for 100 ms after contact with the racket.

The response time was slowest — 33 milliseconds — when sound was present, and when the video clip stopped immediately when the ball made contact with the racket. The slower response time translated to 4 per cent decision errors.

On the other hand, the response time was 21 milliseconds when sound was present and when the video clip ended 100 milliseconds after the ball had made contact with the racket.

What the delay means

What does the delay mean, even if it is of milliseconds, at a professional level, and the court is just 78 feet long end to end (baseline to baseline)? According to the paper, even at 80 kmph speed, a delay of 21-33 milliseconds translates to the ball travelling “two extra feet before the opponent can respond.”

“Our study shows that both response time and accuracy are negatively affected” when noise was present.

Tennis professionals like Martina Navratilova and Chris Evert aver that the grunts block the opponent’s ability to hear the sound of the ball hitting the racket.

Other reasons

But the authors note that there could be two other reasons — grunts may be “drawing the auditory attention away from the sound of the ball hitting the racket and toward the sound of the grunt.” And the third probability — a grunt “drawing the visual attention away from processing the visual event of a ball leaving the racket.”

So the complaints of many tennis players may indeed be genuine. For instance, during the US Open in 1988, Ivan Lendl had complained that Andre Agassi’s noise had distracted him.

“The noise threw my mental game,” Lendl said. “When Agassi went for a big shot, his grunt was much louder. It threw off my timing,” Lendl was quoted as saying in The Sunday Times.