Sooooooooo many questions about teaching S come in that I want to take this opportunity to write out the simplest most direct method that therapists have been using since early in the 20th century. This method is reported in just about every articulation therapy textbook ever written. The oldest reference I have seen for it is Scripture (1912). Scripture’s book is one that Van Riper recommended.

There are dozens of ways to do this, but this is the basic procedure––

1. Make sure your client is producing T correctly. Make sure the tongue is behind his front teeth, and place a straw outside the central incisors to make sure the airstream for T is coming out right at midline [see illustration, right].
2. Teach the client to listen to his T. Make a big deal about how it sounds and how he is making it.  I.e., draw his attention to the acoustic qualities and the tongue-tip elevation and depression pattern.
3. Consider using a tube that is stretched from his teeth to his ear. That was he will hear exactly what you are talking about.
4. Teach him to exhale with prolongation as he makes his T.  I call this a “Long T”.  I tell the client, “Make a Long T by blowing longer.”  Make sure this is a gentle airstream.
5. Once the client can hold the fricated off-glide of T, he basically is producing an S, but it is a little gross, too noisy, and too big.  Too much air is coming through.
6. Teach the client to gently lift the tongue-tip so that it rests closer to the alveolar ridge. He will either lift it higher or not let it drop as low during the off-glide.  He needs to make a tinier sound.
7. Help train his ear to hear all of this as it occurs.

Reference

• Scripture, E. W. (1912). Stuttering and Lisping. NY: Macmillan.