FANS accustomed to the big-match atmosphere can forgive themselves for feeling a little flat tonight, warns an expert in sound research.

Supporters of Oxford United and Portsmouth will only be able to watch the Sky Bet League One play-off semi-finals from behind a screen, with the game taking place without fans.

It remains to be seen whether artificial crowd noise will accompany the coverage on Sky Sports, but games will be played in a very different environment regardless.

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Paul Whitty, head of Oxford Brookes University’s School of Arts, has a special interest in sound research and football.

The professor expects it to be a strange experience for fans and players alike.

He said: “The sounding world of football has completely changed.

“A few writers have said this isn’t football, because you can’t have that same energy of the match.

“It relies on both players and fans being there and their interaction.

“It makes it less of a spectacle – there’s been far less controversy over decision-making than when fans are involved.”

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While crowd noise has been piped in for Premier League matches since football returned, the feature was absent for the League Two play-offs.

As well as the shouts from inside the ground, external noise was also audible and Whitty feels this could be even more pronounced in the second leg.

He said: “When they play at the Kassam it will be really interesting to see the impact of the open end.

“Having the crowd seals it is an object, but instead you’ve got everyday life seeping in.”