Not having a voice for me is also when I'm talked over or someone finishes my sentences. It happens quite a lot at work and it's always bugged me. I've brought it up before with my colleagues but for them they might talk over me or finish my sentence without consciously noticing their doing it so you have to be somewhat sympathetic I guess.
I can honestly say that having a stutter and not being able to have a voice when you want to speak up or you find that you can't is a constant battle. I have improved now that I'm in my mid twenties and I'm more confident and have gone outside my confort zone and conquered my fears as far as public speaking, independence and travelling goes but it's still an uphill struggle and some days I feel like I have no voice at all.