I also cough into the bend of my arm, into what ever clothing I have on, which muffles it pretty well, but I also beleive that if the animal isn't looking at you and sees your movement, no harm has been done. All kinds of noises in the woods, often I can't tell what made the noise, deer are the same. They may look in the direction of the noise, but rarely will leave the area just because of a strange noise.