How do you give stadiums atmosphere?
A good atmosphere at a sports stadium can make the difference for both the players on the pitch and the spectators in the stands. But how easy is it to engineer that sense of crowd magic?
The nickname the Theatre of Dreams for Manchester United's Old Trafford stadium was never intended to evoke a sleepy atmosphere. But the club has taken on an acoustic engineer to see how they can boost noise levels in the ground.
A good atmosphere in a stadium matters to the business people who run sport because it can attract even more ticket buyers.
The boost a lively crowd gives to the home team and the way it can intimidate the opposition can also help bring success, and therefore money, to a club.
So, how can you create a good atmosphere in a sports stadium?
"You have to achieve a connection between the spectator and the event," says Rod Sheard of the Populous architecture practice, which has designed many major sports stadiums and arenas across the globe.
"The closer that is, the better the atmosphere will be."
Sheard says that was the aim when designing the 80,000-seat London Olympic Stadium, which will be turned into West Ham's new home. "We fought hard to keep that a tight bowl, so that the vast majority of the crowd were close. Even the last row felt connected," he says.
Daily Telegraph football correspondent Henry Winter has visited stadiums across the world. "The best ones are like ravines, like the Millennium Stadium in Cardiff, Valencia in Spain and the Juventus Stadium in Turin. You have the feeling of being on top of the pitch," he says.
Creating an atmosphere is not only about generating as much noise as possible. It is also about making the fans feel they are part of an event and giving them an experience they could not get by watching it on television at home.
"It's almost impossible not to be engaged with what's happening on the pitch at the Millennium Stadium, especially when it's enclosed with the retractable roof on and the Welsh rugby fans singing," says Sheard, who worked on its design.
That is not a common enough phenomenon at Old Trafford, according to Ian Stirling, vice chairman of the Independent Manchester United Supporters Association.
"The sound inside Old Trafford is very localised," Stirling says. "I've had season tickets in quite a few places and there will be a lot of atmosphere in those areas, but you just won't hear it down at the other end."
Acoustics is about geometry, says David Keirle, chairman of KSS sports architects and designers. "Noise travels by line of sight. There are parts of Old Trafford where you can't see or hear what's going on in other parts," he says.
Improving the atmosphere in an existing stadium is obviously different to building it up from scratch and Keirle says one solution for Old Trafford could be to pump noise via microphones around the ground.
KSS designed a curved and tilted roof for Brighton and Hove Albion's new Amex Community Stadium, which Keirle says retains the noise and reflects it onto the field of play. "You get long reverberations and people respond," he says.
Keirle has been impressed by the atmosphere at the Centurylink Field stadium where the Seattle Seahawks American football team play, and inside Twickenham for England rugby matches.
Some new-builds have been more successful than others regarding atmosphere.
"Wembley is poor partly due to England's fans, who can be day trippers, and the rake is huge," Winter says, referring to the slope of its lower tier.
Sheard, whose company designed it, says he has attended matches there with a great atmosphere.
"Inevitably when you do a stadium with more than one purpose you have to compromise. It is a big stadium and seats 90,000. If you changed the rake on the first row by a few millimetres that would have an effect of several metres at the back."
But atmosphere is not all to do with design, says Kevin Miles, chief executive of the Football Supporters Federation, and a Newcastle United fan.
"Ticket prices have gone up several hundred per cent since the formation of the Premier League. The age of the fans has therefore gone up, when the atmosphere was created by the younger working class fans. You have to price it accessibly."
Miles says the loss of standing sections, where most of the atmosphere was created, has also had a negative effect. He says designated singing areas - which can be a euphemism for the toleration of standing - have helped the atmosphere in stadiums, such as Manchester City's and Sunderland's.
"The location of the away fans - who can have a disproportionate effect on the atmosphere - is also important. They can spark a reaction from home fans, while a lot of clubs have moved them up into the corner out of the way."
When it comes to atmosphere, Winter believes clubs could learn a lot from Germany's Bundesliga, where standing sections exist and tickets can cost a fraction of their English equivalents.
"At Borussia Dortmund and Bayern Munich they have a strong fan culture and you don't get that opera-style attitude from the fans of, 'you entertain me'," he says.
Borussia Dortmund fans are known for their coordinated displays of murals at matches and many were impressed by the show they put on ahead of Tuesday's Champions League quarter-final against Malaga.
Winter and Miles say the atmosphere at Galatasaray's derby matches in Istanbul takes some beating. The passion of the supporters is a major factor, according to Winter.
"Marseille is unbelievable because of the fans. Architecturally the Stade Velodrome shouldn't work, but it doesn't matter," he says.
Architects admit they can only provide part of the jigsaw puzzle that makes up atmosphere. "We can help the process with design, but we can't make it happen," Sheard says.
Winter has one final piece of advice for any team trying to improve the atmosphere in its stadium. "Playing good football is the best idea," he says.