Are we discussing flinching, or cringing? I'm not really sure on the distinction we've got going here.
I will only flinch, as I know it, if I think something or someone is about to hit me. So, you know, I pull my face away from it, and usually tense up.
But I cringe at certain sounds/feelings. Like, if someone bites metal, particularly if they bite their fork while eating.
Or if finger nails get caught on something (not the sound of them scratching, so much as them getting caught in fibres of materials).
For me, I suppose I consider cringing to be a result of disgust, whereas a flinch is a fear of physical danger.