Source of D sound
Is it true that the Spanish "D" is pronounced like a person with a lisp because centuries ago a king of Spain had a lisp?
3 Answers
Actually, you have the story right but I think you're thinking of the soft 'c' (before 'i' and 'e') and the 'z'; according to the tale, in parts of Spain (but not in Mexico or any other part of Latin America) those sounds which in other places are still pronounced 's' are now pronounced 'th' as in 'thick' and 'thin'. The 'd' sound is actually a little like a 'th' but it's more of a hard 'th' like 'that' and 'the,' and it has nothing to do with the king, to my knowledge.
As PC said, you have the story right, but even though that tale has been told for decades, it is really not true. A litlle research on the internet will show that the development of the Castillian ceceo is a myth. Here's one link that will explain it a little.
The "th" sound has various strengths depending on where it falls in a word, ie: donde. Here on the first D "th" is very slight. The second D has a little softer sound.
In ciudad the first D is soft like the second D of donde. The last D because it the final letter of the word has an even softer sound, which could called a lisp sound as the sound is drawn out more than the other Ds..
So even without the correct history that Noetol has provided, the actual pronunciation kills that silly theory.