No particular difficulties are universal; each individual has his own stumbling blocks. On the whole, consonants like ‘m,p,b,t,d,k’ and ‘g’ create blocks, whereas sounds like ‘f’ and ‘s’ result in prolongations. The stutterer with above average intelligence quickly learns to avoid word knots and to use synonyms so that no mishaps occur – in the process often acquiring a vast vocabulary. For example, if he thinks he’ll get stuck on “business”, he’ll say “commerce” or “enterprise” or even “small industry” instead of the dreaded word. However, this substitution often reinforces the poor self-esteem that the stutterer suffers from. When a word cannot be by-passed, it is a common trick to add a set phrase like, “You know what I mean” which the stutterer hopes will carry him over the difficult words on the whole.