There has been research in to how our unconscious mind functions while were asleep. Im sure you’ve heard of experiements in which subjects listen to tapes play while they are asleep. So technically yes we can hear them but do we comprehend and store this information, probably not. Im sure Canalon will clarify this even more.

try out speaking things abt a slept person near him/her… & u’ll get that!
For why is it like that, i think bec. our brain rests to get itself chemically potent to do work with greater efficiency…
But the BRAIN MUST BE REMAINING AWARE ABOUT SOME SENSES OF UNSAFENESS…but as human life is far from natural, the sensitivity seems to be lowered…

Sorry I don’t like to post to say that I have nothing to say, but since you call my name, i just come to apologize for my complete ignorance on the subject.

People who are in a coma
hear what is being said
although they do not realize it
they have dreams about what is being said.
🙂
And it is noise that can wake you up from a deep sleep.
and hearing is the last thing to go before death

i have drempt about goosebumps once when i left my tv on when i was off ill.
also i can listen and understand the radio while asleep and recall recent subjects too :\

i don’t think it is possible to know anything around u when u r REALLY in deeeeeeeeep sleep 😀
That’s why sleeping drugs r given before a person is operated.
VeenaandNivyah

The state the person has when he is sleeping and when he is under general anstesics is not the same. During in operation, you can literally play a rock concert near the pacient and he will not wake up. But try to operate someone when he is sleeping, and you will probably get a punch in the face.
About the sleeping person hearing what is said around him, it depends on 2 parameters: how deep he is sleeping and how loud you are speaking. We have 2 kinds of sleep: REM and non-REM in a sleep cycle. Out of a total of 90 minutes, REM phase only lasts 10 minutes. In the REM phase, you are dreaming, and you are much easier to wake. it is in this phase that you are more likely to hear words spoken. In non-REM phase, or deep sleep, you are more likely to not hear the words.
But as i said, it really depends on the intensity of the sound.