Grunter: Rafa NadalCredit:ALEJANDRO GARCIA/EPA-EFE/REX/REX Jimmy Connors in the 1991 US Open.Credit:Focus On Sport/Getty Images North America The results showed that the tennis players were pretty accurate when it came to estimating the lateral variation of the resulting bounce, but consistently over estimated the length of the opponent’s shot after a particularly full-throated snarl.The louder the grunt, they seemed to reason, the harder the shot, with a consequent incorrect prediction of where the ball would land. Tennis players should take note: to take the advantage, one should make a right old racket. Along with random bursts of rain, overpriced strawberries and the perennial agony of supporting Andy Murray, tennis fans have often complained about another feature of the modern game: grunting.The controversial feature of professional tennis, thought to have been initiated by Jimmy Connors in the 1970s – who famously once said he hated to lose more than he loved to win – has been blamed not only for spoiling some games, but also for influencing the results.Maria Sharapova, the 2004 Wimbledon champion, has been heard to shriek on court at 109 decibels, the point at which an average human experiences pain and the equivalent of standing 200 feet away from a jet aircraft taking off.Former world champion Martina Navratilova has in the past said the excessive crepitations heard around court is “cheating pure and simple”.The usually unflappable Roger Federer, Swiss winner of 20 single Grand Slam titles, is equally deuced: “I’m OK with it to a certain level, but I don’t like it if it’s too loud or it’s used in key moments,” he has admitted.“That becomes unsportsmanlike.” Previously it was thought that the act of one player bellowing as the ball is struck simply distracted the opponent. But now a team of scientists from the Friedrich Schiller University, in Jena, Germany, suggest there is more at play.The scientists asked 31 club level tennis players to watch video clips taken from the 2012 Barcelona Open finals between Rafael Nadal and David Ferrer.After watching a shot and hearing the accompanying grunt, the observers had to predict the ball’s trajectory and indicate where it would land. They were not told that the scientists were manipulating the volume of the grunts. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. For many years sports psychologists have been attempting to unravel the role of auditory perception in sport in a bid to discover exactly what impact grunting has.