A woman in a male-dominated field

Those of you who know me know that I work in male-dominated fields (engineering and construction). For the most part I feel like I am treated fairly and am respected by the men with whom I work. However, there continue to be remnants of male chauvinism that rear their ugly heads. Even though I am the one making the final decisions, some of the men tend to ask the other men on my team rather than talking to me. The other day, one of the engineers with whom I am working blatantly challenged my request, but listened to the men who reiterated what I had requested of him. I try not to be paranoid about it, but sometimes it is hard to ignore the fact that being a woman in this field is still a bit of a novelty, and some men don't know how to respond. When I see or hear gender-biased responses toward me, I usually choose to ignore them and act as if the person didn't mean it. I am of the opinion that if I act with the expectation that they respect me, they will in respond in such a manner. Unfortunately, sometimes it doesn't happen, but I am learning to live with it.