(CNN) Tennis fans heading to the French Open with a sensitivity to noise might want to treasure the coming fortnight at Roland Garros.

That's because after the conclusion of the season's second grand slam tennis is about to get louder -- much louder.

Grand slam winners Maria Sharapova and Victoria Azarenka have long been considered two of the loudest grunters in tennis and the sounds stemming from their mouths -- instead of their tennis rackets -- might just attract more attention at Wimbledon in July.

"It'll be a scream on centre court as women face off" was the headline adopted by Melbourne's Herald Sun five years ago on the eve of the Australian Open final between Sharapova and Azarenka.

Sharapova -- who returned to tennis in April after serving a 15-month doping ban -- wasn't offered a wild card entry for the French Open but is expected to make it through qualifying and land in the main draw at Wimbledon -- tennis' most prestigious tournament.

Meanwhile Azarenka, who also isn't competing at Roland Garros, hinted in a tweet last week she would surface at the famous SW19 postcode after intending to make her own comeback -- the Belarussian gave birth to son Leo in December and hasn't played since last year's French Open -- at a Wimbledon warmup.

Do you understand how to use noise?

But are tennis' grunters misunderstood?

While some TV viewers in the past have complained about the loudness of grunts and other fans have opted for earplugs or even mimicked those sounds when in the stadium, it turns out that grunting can aid performance on the tennis court.

"The emotional value is one, no doubt," Alan Jones, a London-based tennis coach with 50 years of experience, told CNN Sport. "Exhaling to the point of contact is two."

Jones is most famous for his partnership with Jo Durie, who reached a highest ranking of fifth in the world in 1984. He urged Durie to "make lots of noise through impact."

Do you understand how to use noise? -- Alan Jones

Decades later, it's advice he gives youngsters in the infancy of their careers.

"Look at martial arts," he said. "And if you listen to boxers when they are giving their blows. Why would you hold your breath in?

"I've got a player now who I really think will have a great shot in two or three years' time. She's a great tactician and at the moment is an athlete with a tennis racket.

See you there SW19 https://t.co/YhIZxz6oBK — victoria azarenka (@vika7) May 22, 2017

"I'm trying to convert her to a tennis athlete. One of the things we're doing is at the moment of impact, do you understand how to use noise?"

Jones suspected that players who grunt are able to generate more pace and a study conducted by the University of Nebraska , Omaha confirmed as much.

Velocity increases

Ten players from the US top tier Division I -- five men and five women -- were placed in different groups. One group was told to grunt while the other wasn't.

The grunters, in a combined hitting session of 20 minutes, registered increased velocity of 3.8%.

"We speculate that grunting may allow a greater utilization of energy from the elastic components of the large trunk muscles which would provide more energy for hitting without increasing the energy demand," Kris Berg, who oversaw the study, told CNN in an email.

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The findings wouldn't have surprised Jonny Fraser, who holds a Master's degree in sport and exercise science and owns Science in Tennis in Sheffield, England.

"If you think about grunting and relate that to strength and conditioning, what we do in strength and conditioning is we talk about using that breath, that inhalation to stabilize your spine but generate more force ultimately," Fraser, a former county tennis player, told CNN.

"From a tennis perspective and what the science says is that it helps improve muscular recruitment, to take that breath in, it stabilizes your spine and helps your muscular recruitment around areas such as your trunk muscles, so things like your obliques and your pec major," he added, referring to the chest and sides.

"So as you come through it helps to generate that little bit extra force as you strike the ball and that leads to increased velocity."

By taking that deep breath, said Fraser, not only does one create more muscular force but the state of relaxation increases.

"The more relaxed you are, the more force you are going to generate," he said.

"If you think about a hosepipe with a kink in it, if you're tense and nervous, the amount of force that can go through that hosepipe and that whole chain of your body will be reduced. It's the same in tennis."

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101 decibels

Even so Jones and Amanda J.N. Owens, a performance and sports psychologist, feel the grunts of Sharapova and Azarenka are excessively loud.

Yet grunting and exhaling as a whole sharpens focus, according to Jones. Players might otherwise dwell on an unforced error, bad call or worry about what the opponent is doing.

"Sharapova does have the ability to focus very quickly," Owens, a former player who now owns Believe consultancy, told CNN.

"And grunting for her is her way of focusing and getting in the present and creating the flow and rhythm. It's just beautiful to watch.

"Psychologically, exhaling releases more power in the shot. If you hold your breath in, it tenses the body."

Sharapova's grunts were once measured at 101 decibels -- similar to a jet taking off -- so her level certainly exceeds most on the tour. She told Reuters in 2012 that grunting was simply a "natural habit" and not taught.

Gamesmanship?

Grunting, however, isn't confined to the women's game. Far from it.

Men's pros, including Rafael Nadal, regularly grunt, with Andre Agassi famously drawing rebuke from Ivan Lendl in the late 1980s for his audible exertions.

"I was practising next to Nadal, and he grunts louder than me, and nobody notices that. Why?" asked Azarenka at Wimbledon in 2015.

Former world No. 1 Caroline Wozniacki has claimed some players grunt as a form of gamesmanship. Lendl said following a match against Agassi at the 1988 US Open that his rival's grunts affected how he heard the ball come off the strings, a key component in anticipating the strength and direction of a shot.

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The head of the WTA, Steve Simon, told reporters in Miami in March that he didn't plan on taking any action to lessen grunting, five years after predecessor Stacey Allaster sought to formally address the issue.

Grunting and the debate surrounding it will probably never stop but the benefits are clear.

"There are many byproducts to it," said Jones. "It influences how you feel in the moment of crisis. You can release it. It's not just about the strike.

"It can add such good value to a competitor, to make them feel good."