I was recently discussing with a friend how the Barcelonans actually call themselves “Barthelonans”. He then regaled me with an amusing story as to why, saying “TH” for “S” is actually peculiar to Spanish speakers in that region of Spain. The phenomenon is called Ceceo. Very few Spanish speakers in other parts of the world use this form of pronunciation. Legend has it that Pedro of Castile lisped, and that the population – either to ingratiate themselves to the king or not offend him, adopted the lisp! Great story really, but unfortunately when I looked into it, a legend.
The use of the Ceceo pronunciation actually predates Pedro of Castile, and no one really knows its origins for sure.
In Australian English (and all other English forms) pronouncing “s” as “th” is referred to as lisping.
Until about 3-3.5 years of age lisping is considered developmentally normal – that is, it’s not unusual for children under this age to lisp. However, if this speech pattern persists after 3.5 years of age, children usually require help from a speech pathologist to assist them to pronounce their “s” sounds correctly. It is certainly important to seek some help before children start school, because sounding out “s”, but saying “th” makes learning phonics in spelling very confusing! Also having children essentially practice the incorrect pronunciation for a number of years, often makes learning the correct way more difficult and time consuming.
That said, at Eastside Speech we also successfully treat a number of adults that didn’t have the benefit of speech therapy as children- they tell us that they are “tired of speaking with a lisp”. So it’s never too late, but as with most things, the earlier you seek help the better.
Find out more about Speech Therapy for Adults