Yep, i usually get blocks on the "K,P,T" letters (consonant i believe?), but the worse sounding stutter comes from indeed letters like s , especially if the s goes with t. If i get blocks on consonants then there will be no stuttering sound, but if its on s, it goes like sssssss and you try to say something infront of it to make it easier to say, it goes like ssssss um sssss um sss, not my proudest moments.