When I was in elementary school every student had to take the speech class. This was a place where we were taught public speaking and where speech impediments were addressed as well. Such a class does not seem to be in the curriculum any more.
I sometimes wonder if this is the reason that there are such a large number of entertainers, politicians, and other personalities who speak with a lisp. Many children start out speaking with a lisp, but they grow out of it. Why are there so many that do not? That being said, how do so many who lisp get jobs that require them to speak as the main part of their job?
Humphrey Bogart had a lisp that was attributed to bad dentures. What excuses do the others (too numerous to mention) have?
Foreigners have an excuse for pronunciation problems because certain sounds do not exist in their languages. The “th” sound is difficult for the Germans and French. Asians have difficulty with “l” and “r” sounds. The guttural “ch” sound as in “challah” and “Chanukah” is difficult for some.
However, the correct pronunciation of the letter “s” is simply a matter of proper placement of the tongue. Extending the tongue between the upper and lower teeth or pressing the tongue against the lower teeth is incorrect.
Bring the tip of your tongue up near the upper front of your mouth, but do not touch it against your teeth. This should form a groove down the center of your tongue, allowing air to flow when exhaling though the mouth. The mouth should be open slightly.