can i listen to AUM mantra while meditating instead of chanting it?
In your question saying "listen to AUM mantra" I believe you are referring to listening to a recording (a CD, I suppose) while meditating (versus inwardly or even outwardly chanting AUM).
Listening to a CD can be a good way to, perhaps, begin your meditation but to truly meditate it is important to cease all outer sounds (even chanting with the voice), and LISTEN DEEPLY to the silence within.
In fact, yogis teach to listen inside the RIGHT EAR while meditating (not the entire time, necessarily, of your meditation time, but while trying to listen intuitively for the AUM vibration).
No matter what meditation techniques you use, it’s always good to reserve the last quarter or third of your sitting time to be still, to be receptive, and to commune inwardly with whatever state of higher awareness you’ve been blessed to experience: peace, calmness, AUM, Light (Jyoti), love, joy and so on.
Sometimes this last phase of inner communion is briefer than 1/3 or 1/4, it just depends on your own state of mind, but it IS important to seek stillness. This is where real meditation can begin and where the sixth sense of intuition is developed.
Earplugs or headphones can be a help. Best is to learn the AUM TECHNIQUE of meditation. This involves a mudra and arm rest and is taught by Ananda in person or by correspondence or online classes.
Chanting AUM aloud or inwardly is excellent but our real goal is to actually hear the sound of AUM within ourselves and to commune with AUM as the vibratory manifestation of God the Holy Spirit (or Divine Mother) IN creation. The rishis have gone so far as to say that communion with God as AUM is our highest duty.