Dear Kwesi,
“Mind chatter” is a very common challenge in meditation: the mind easily spins and spins. For that reason pranayama (breathing and energy control) has been taught for centuries. Yogananda taught, as one example, the triangular breathing technique: inhale, hold, exhale, always for the same count, and always through the nose. Practice 6 to 12 times. Consciously breathe calmness.
There are other useful pranayamas which you can find in Swami Kriyananda’s book The Art and science of Raja Yoga. It’s good to explore them and see which one works for you.
After pranayama you need a good meditation technique: at Ananda we teach the Hong-Sau technique which Yogananda taught. It calms the mind. Please remember that quality is more important than quantity. Don’t meditate for a long time if the mind simply runs away. Instead, first practice long pranayama, then your technique, then, whenever the mind is uncontrollable, do some affirmation practice, or chant, or repeat a mantra. Be patient. The mind simply is very hard to “catch” and stop.
Concerning the voices you hear: most probably they come from the subconscious mind. One can see pictures and also hear sounds and voices from the subconscious. Try to meditate with your eyes half open, which will prevent you, I hope, from opening the door to the subconscious world. It might also help your concentration. Yogananda taught that half-open eyes are a perfectly good way to meditate. Look slightly up without strain in your eyes. Don’t look down. If these voices still come, don’t give them any attention. Concentrate on your technique as best as you can.
Be regular in your meditations (meditate daily). Otherwise progress may be slower than you would like.
All the best, may God bless your meditative efforts,
Jayadev