Andy Murray wrote on Twitter about his second round match at Wimbledon 2013, “There’s a bit of me that misses there being no roof… @wimbledon still looks and sounds weird watching grass court tennis indoors.”
How does the roof affect the acoustic within the arena? how does the sound of racket on ball change and why?
From thwack to thwock
In the 2012 final at Wimbledon, Roger Federer and Andy Murray started playing with the roof open, but torrential rain forced the roof to be closed for the later sets. Listening to the start and end of the game, you can hear the difference the roof makes. The thwack last a little longer, echoes a bit more and sounds fuller.
Roof close (listen to the serve):
If you are struggling to hear the difference, turn up the volume and maybe put headphones on. Looking at the two waveforms, each ball strike can be seen as a spike (there are 5 in the top graph, 4 in the bottom plot). What is noticable is that the other stuff, the ‘grass’ along the middle of the plots is taller when the roof is closed.
With the roof open, sound going up towards the sky disappears never to be heard again. With the roof closed, the sound reflects off the roof and is trapped in the arena. As it bounces around these reflections are heard to elongate the thwack of the ball.
The roof also traps and amplifies other sounds like the noise from the crowd and the grunting of the players. Does this enhance the experience of spectators? What do you think?