Consider that your thoughts are actually audible, i.e. they are making sounds. If you can hear your thoughts, you are making sounds. And everyone else can hear your thoughts too, like being in a room having a conversation. I don't mean that there is a thought and there is a separate sound, I mean the thought IS the sound. We're so used to believing that all our thoughts are private that we let them run wild and unchecked, as though they impact nobody else. For the sake of this meditation, "there are no private thoughts!" - ACIM
Then imagine that you're in some place where, for whatever reason, you have to be very very quiet and not make any sound. Maybe you pretend you're in a library or a church or something. You don't have to picture anything particularly, you just need to know you need to be quiet - your audible thoughts need to be quietened down.
The main thing is simply 'being quiet' mentally, which basically means, not creating thoughts because they would disturb the peace. Since you know your thoughts are going to make sounds that are heard, and you need to be as quiet as possible, this simply compels you to focus on being quiet.
This isn't the same as thought control. You're not trying to stop thoughts once they've happened. You're just being quiet so that you do not make thoughts in the first place. And since your focus is on 'being quiet', that's enough to stop them arising. IF thoughts start to pop up you can bet you have 'failed' to be quiet because now your mind is chattering, and everyone can hear you! Shhhhhh!
I find this is easier for me than trying to be 'still', because stillness for me is too associated with lack of physical movement or not breathing and it just makes me become tense. I also find this easier than trying to focus on my breathing or breathing in a particular way or 'thought watching' and trying not to get caught up in thoughts. That's hard. Once thoughts are created they kind of have a mind of their own, because they are like little created beings with their own little bit of consciousness going off in random directions. Not making thoughts at all bypasses that. It's much easier to be quiet when there are no thoughts to deal with, than to try to clean up a noisy thought-mess after it's been triggered.
Once you've been doing this for al little while your mind should quieten down. In fact you should be able to 'be quiet' very quickly. I find this works far more effectively than other meditations I've tried.
While you're being quiet, take the opportunity then to calmly have a conversation with Holy Spirit or Jesus. Hearing them entails 'listening' which means not broadcasting your opinions and viewpoints, or your background 'processing' of what's being said. If you want to hear their voice, you need to stop your mental yacking and become receptive.Your thoughts ARE a conversation. And as the course says, the degree you will hear their voice is the degree that you're willing to listen.
Holy Spirit and Jesus are happy to talk to you if you will listen enough. Give it a try.