What are those things the audience wear in the right ear at snooker tournies -it looks like a headset of some sort but why?

They are ear pieces which enables the audience to listen to the commentary like you would hear on television. They are available to buy from the venue and cost in the region of £5. They can be used again so that you don't need to buy one for every tournament.

They are Sound Dec radiOS. They are available all over the sporting world really, Cricket Rugby Snooker, Badminton Horse Trials, Squash, Swimming, Gymnastics. They are everywhere.

I found their website from my old radio from the cricket See the related link.