How does sperm get the information about the release of egg?

Question

How does sperm get the information about the release of egg?

Answer 1

I don't believe sperm need a notice of ovulation, they naturally seek eggs, attaching to the zona pelliculada if one is found. If there is no egg, the relatively short-lived sperm will eventually die away.  

Answer 2

I don't think they do, they just keep swimming until they die or hit the egg.