I've seen it in so many talented young women who hold back because they're not sure that what they say will be smart enough. Or maybe they've said something in a prior meeting, and people acted like they hadn't said it, and that was crushing. Then we have all had the experience where 20 minutes later, a man says the same thing and everybody responds positively.... So don't take it personally. Take it seriously so that you understand it, and then try to devise techniques to overcome it.