This Is Probably Impossible, But.... Making a link work only once.

I would like to know if it is possible to do something to a hyperlink so it only works once.The reason I am asking is because I am trying to organise a sort of online "Name that Tune" competition, ie. people click the link, and the piece to be recognised is played for 20 seconds.Obviously, just like on the live show, people should only be able to listen to the sound clip once, rather than keep clicking to hear the sound clip again and again.Is there a way to achieve that?Thank you.

I don't know the implementation for it but for the "logical" solution I'd say to use a PHP script that adds a cookie to the PC. If this is found, it would not allow re-listening to the clip.As an alternative, you could log IP's and use that information to decide whether or not someone should be allowed to listen to it.A couple of problems, however:1) Both of these can be bypassed (but most people wouldn't know how)2) People can download the clip (same point as above)