I found a website. It's on a TV show you american guys has I think. Anyway, I dunno what it is, but I found something quite creepy on it. Take a look:
http://www.cbs.com/primetime/ghost_whisperer/real_ghost/
There are enlarged photos of three ghosts. Below, you can listen to recorded spirit's voices that people caught on tape. Some of them were caught while playing the tape in the 'reverse' mode.
I listened to two of them, 'I love you' and 'I found you there'. I was too scaredy cat to try the three others.
Here, we can share our opinions about white noises. What do you think? A tape trick or something real? For my part, I think some might be real. I believe strongly in paranormal events and is quite open to all the new unexplained events I can find on the web...do you?