Heightened awareness is normal and when the mind becomes very still you will be able to hear external sources more easily. This occurence may come once and then not re-occur for a year or may come naturally to you depending on where you are in the process of your personal "Way".
As for seeing through your eye-lids, this is often thought of as a lucid dreaming type state, however if you have a lot of energy in the third-eye area it is not uncommon to have extraordinary visions and seeings such as the one you described. Often people experience seeing things such as planets, asteroids, comets, galaxies, faces and just about anything you could dream up (ie. aliens, flying pigs, sheep jumping over a fence =) -
Insure that you are spending some time grounding yourself before you partake in your meditation, meaning either standing with your feet flat on the floor and breathing the lower-dantien and exhaling downwards through the feet energetically connecting with the ground.
Have fun with your meditation.