Rafael Nadal
Scientists are trying to predict who will win Wimbledon based on the noises players make in the game. Getty Images

Jordan Raine, University of Sussex

It's that time of year again. British hopes and dreams weigh once again on one shy Scottish bloke's shoulders. Expectant fans will throng together on Murray Mound to eat strawberries and cream and talk up their hero's chances. Can he do it again? Is he mentally prepared for the challenge?

New research into the noises that Andy Murray and so many of his fellow players make during matches could take out some of the guesswork about how they feel they are performing.

Grunting is now an established – if controversial – part of Wimbledon. So much so that former prime minister David Cameron joked a couple of years back that spectators should bring earplugs. In fact, since its popular emergence three decades ago, it has consistently divided opinion in the tennis world.

The earliest prominent vocal culprit was Monica Seles, who consistently drew fire for her shrieks. Since then, the phenomenon has become commonplace on both the men's and women's tours, but not without resistance. The volume of Maria Sharapova's and Michelle Larcher de Brito's grunts has been compared to that of a chainsaw or a lion's roar and, in the aftermath of one particular outbreak of grunting controversy, Martina Navratilova labelled it "cheating pure and simple".

Her gripe was that grunts drown out the sound of the ball hitting the racquet, which hinders players in assessing the speed, spin, and cleanness of the incoming shot. She has a point too – research shows that silencing Sharapova's grunt improves the perception of the speed of her serve and that white noise might impair an opponent's perception of shot direction.

Roaring success

Others in and around the game defend the guttural groans. Many players are unperturbed by the noises, while others question why complaints focus almost exclusively on female players in a sport full of fairly vocal young bucks. Sport psychologists argue that grunts improve psychological focus, motivating players to exert maximum effort and allowing them to perform in a more relaxed, subconscious state.

It's worth remembering that after the criticism Seles received in her quarter and semi-finals at Wimbledon 1992, she lost heavily in the final, having made a vow of silence she later strongly regretted.

In her silence, Seles may have suffered not only psychologically, but physically too. A number of recent studies demonstrate that grunting allows players to hit the ball significantly harder, without increasing their heart rate or oxygen consumption. In a sport where a point here and there can be the difference between winning and losing, this extra oomph is vital.

Winning and losing

Now, our latest research shows that grunting may confer advantages not only to the vocaliser, but to the opponent too. Analysing 50 matches featuring some of the world's top 30 tennis players, we found that players produced grunts that were higher in pitch during matches they lost than during those they won.

Moreover, while the pitch of players' grunts increased as matches progressed, the difference in pitch between losses and wins was apparent from the early stages of matches, and didn't change in size as matches wore on. Therefore, it seems that the shift in pitch when winning versus losing is not due to players feeling the progressive effects of scoreboard pressure, or revelling in racking up set after set.

Instead, this difference may reflect longer-term physiological or psychological factors that may manifest even before matches begin. For example, the results of previous encounters, form, world ranking, fatigue and injuries could all influence stress and perceived dominance ahead of matches, which are both known to affect the pitch of our voices.

Maria Sharapova
Maria Sharapova has been known to be a vocal opponent. Julian Finney/Getty Images

Most importantly, we found that when competitive tennis players were played short clips of professional players' grunts (with no access to visual cues), they could identify which of two grunt sequences produced by the same player came from a match that the player lost. Our research therefore suggests that tennis grunts may provide opponents with a valuable window into the other player's mindset during a match.

Listeners' accuracy was only 10% above chance levels, likely because players' grunt pitch varies substantially across and within matches, so this is by no means a fool proof way to systematically predict the outcome of a match. But, with prior knowledge of a player's "usual" grunt pitch, it's certainly something that viewers, opposing players and even broadcasters might consider paying more attention to. Players who have faced each other multiple times may already consciously or subconsciously pick up on these cues. If so, such information is likely to influence their confidence, as is the case with basketball players responding to visual changes in nonverbal behaviour.

Dog, deer or Djokovic?

From a broader perspective, this research firmly places human nonverbal vocalisations in continuity with the calls of other mammals. Numerous studies have shown that nonhuman mammals use information contained within vocalisations as key influences on behaviour and decision-making in numerous contexts. For example, male red deer use the roars of competing males to assess their size, and therefore who is likely to emerge from conflict victorious.

Humans are no exception. Like red deer, when we produce vocalisations in a competitive setting, we broadcast information about our internal state, which listeners can use to inform how likely we are to win. Because anatomy and physiology affect the vocal apparatus – the larynx and vocal tract – of all mammals in the same way, vocalisations broadcast information about vocalisers' physical attributes and internal state, whether dog, deer, or Novak Djokovic.

Should we then be paying more heed to other primitive sounds like these? While our conscious attention is focused on the words that we speak, nonverbal vocalisations pepper our daily interactions; from grunts, laughs and sighs, to moans, roars and cries. Many of these noises are highly similar to calls produced by other mammals, and likely communicate a wealth of information that has surprisingly been barely investigated by scientists so far.

Perhaps we know so little about human vocalisations because we feel embarrassed to acknowledge our animal self. In my view, they're certainly nothing to be ashamed of – so the next time you hear a tennis grunt, embrace it as part of our nature. But remember, that noise might be revealing more than you think. I wouldn't go placing any bets on Wimbledon while blindfolded though.

Jordan Raine, PhD Researcher, Nature and Function of Human Nonverbal Vocalisations, University of Sussex

This article was originally published on The Conversation. Read the original article.