Question
Should there not be a distinction between the pronunciation of the letter "sin" and "samech"?
Answer
Shalom Rav,
I have heard of this theory.
The samekh and the sin are pronounced identically by all 'edhoth of 'Am Yisrael.
It is reasonable to assume that once there was a difference, but without a living M'sora it is impossible to be certain.
Hazaq uVarukh,
DHY