Q: I have a client with a lateral lisp, and I have started trying to elicit an S with the tongue tip down. I call a tip-down S a “dipper” and a tip-up S a “tipper.” The dipper position has helped him, but I can’t find any information about the validity of using such an approach. Can you point me in the right direction?

I love your terms “tipper” and “dipper.” Excellent shorthand!

The tipper and the dipper are allophonic variations of the same phoneme.  In other words, they represent two different but acceptable ways of saying the same sound.  In fact, a correct /s/ can be made with the tip pointing up toward the alveolar ridge, or down to a spot below the bottom edge of the lower teeth, or anywhere in between.  It does not matter in what direction the tip points, as long as the midline channel of air can be achieved and the phoneme “sounds” correct.

This viewpoint represents good old-fashioned phonetics, which is the body of knowledge upon which articulation therapy rests.  We do not need research to support or disprove the validity of teaching tippers or dippers. It does not matter which we teach as long as the client and you, and perhaps the family, like the way the phoneme sounds.  We teach what needs to be taught, and we do what needs to be done. Period.

[Please see my article What Evidence-Based Practice (EBP) Really Means and my posts in this blog’s category Evidence-Based Practice.]