I am trying to learn Dutch and I am struggling to produce the /s/ phoneme in the same way that some (most?) native speakers do. It seems that the usual pronunciation is such that it sounds closer to [ʃ] than to [s]. Actually, it sounds very close to the apical /s/ of Castillian Spanish, but not quite the same. Wikipedia says the following:
In the Netherlands, /s/ and /z/ may have only mid-to-low pitched friction, and for many Netherlandic speakers, they are retracted. In Belgium, they are more similar to English /s z/
But how retracted is it? How much should I retract my tongue? How does it compare to Castillian /s/?
What exactly does “mid-to-low pitched friction” mean? How is the production different from that of regular pitched friction?
Which dialects and sociolects have this distinct pronunciation?
To put it in a single question: how is /s/ produced in Dutch dialects?