How to deal with the extreme social hierarchies in research meetings?
I think the previous answers make some assumptions that I am uncomfortable with: they describe how academia should work, but not always how it does work, especially for people who are from disadvantaged groups.

For a basically healthy academic community, I think the advice in the other answers is pretty good about essentially how not to block oneself.

A lot of academic communities are so not healthy, however, and often in ways that are not readily visible to their privileged members.  For example, I have female colleagues who have frequently had the experience of having their ideas denigrated and dismissed for apparently rational reasons, then hearing the exact same idea readily accepted when spoken by a man.  Or there may be a power-clique and anybody who isn't "blessed" by the clique may have a much harder time being heard.

Some academic communities are also simply downright toxic and not good for anybody.  I have seen groups where any sign of weakness meant students and postdocs would start verbally attacking one another, trying to gain favor in the eyes of their professor.

I think the first thing to do, then, is to try to get some perspective on what type of academic situation this really is.  Find some more experienced friends or a faculty mentor outside of the group that you can trust and who is generally "good at people", and talk to them about your experiences---not your feelings, but the actual words that people are using.  That person can then help you figure out whether the problem is in the group or in yourself, and what the best path to take is, whether it is changing your attitude, improving your standing, or simply finding a different group.