confusing question, but letsee...
sit alone in your house, the tv/radio turned off, everythings quiet. sit in a meditative state [cast a circle if you're worried] and ask 'is anyone here?' or 'hello' or something like that. from here you must listen. you may here movement, like footsteps, or perhaps a reply to your question. if it's movement, make sure it's not a pet, or a family memeber returning home or something. voices are different for each spirit, so there isn't an exact 'they will sound like this' explanation. it should sound like someone's talking to you. how you talk with your friend, you hear their voice and you can tell it's not your voice? that's what i mean. sometimes a voice can sound like it's all around you [typical for demons, but demons are rare to meet unless invited] or louder in one are of the room. or they'll talk so fast or high/low you can't make out works, but you can tell someones speaking.
another way to 'hear' spirits, when using a pendulum, typically, my friends and i sense/hear a voice in our heads with the answer before it moves.