This incident happened with me today, that is 17th November 2014 at about 2:30pm in the afternoon in the college. We were total five people: myself, my friend Diya and her boyfriend Vicky and Pari and her boyfriend Shawn (names changed).
We had our lectures off so decided to chill out and also the couples needed their privacy. We decided to go in one of the empty classrooms. The college has two buildings 'A' and 'B'. We were in the 'A' building and the classroom is quite small, mostly occupied for extra lectures and is very dusty with any how arranged benches but is well ventilated and has two large windows.
Here the main story starts. Diya and I were sitting on the second bench, and Vicky just behind us. I was very bored after sometime so decided to take a nap. I simply rested my head on the upper desk and was trying to sleep. There was a moment wherein I was half asleep and half awake and suddenly I heard that a girl is speaking something. The voice was clear and was just like someone is sitting just in front of us but we were actually only 5 people in the classroom. I just regained my senses and fully woke up and looked up to find that there was nobody actually! I thought it was Pari but she was quietly noting down something while Diya was reading some stuff.
Again I tried to sleep, but was totally awake and again heard that 'girl' speaking. I looked outside the window to find out whether anyone from the B building was speaking loudly as the whole campus was quiet and no one was there in the B building. All the classrooms were vacant.
It was impossible to hear anyone so clearly if speaking on the ground.
It was very weird. I started feeling strange but just shrugged it off. Still confused about it.