Is ᄉ voiced under the same conditions that cause ᄀ, ᄃ, ᄌ and ᄇ to be voiced?

Question

The Wikipedia article on Korean phonology says ᄉ can be voiced just like ᄀ, ᄃ, ᄌ and ᄇ:

[The] characteristics [of /s/] are nearest to those of plain stops, as it generally undergoes intervocalic voicing word-medially.

However, I don’t remember ᄉ being mentioned in voicing contexts in most materials I’ve read. Have I just been blatantly missing it, or is the situation of ᄉ not that straightforward?

(I could say I don’t really notice it being voiced when listening to e.g. ‘의사’, but neither am I experienced with spoken Korean nor do I actually trust my ears in situations like this. At all.)

PS: I’ve just noticed that it isn’t given as voiced either in Wiktionary entries, e.g. ‘의사’.

Answer 1

I think the Wikipedia article is wrong. I've never heard ㅅ as a voiced sound.

(Hopefully someone who knows Korean phonology better could give a more definitive answer.)

Answer 2

It depends on the situation. So you learned that when you read just ㄱ, ㄴ, ㄷ, ㄹ, ㅁ, etc. you have to put ㅏ. If you pronounce it like this way, ㅅ will sound like ㄷ. However, if you just want to pronounce ㅅ, it will sound like ㅈ. But normally, we put ㅏ, so it is voiced under the same condition that causes ㅈ. Does this make sense? I'm not that good at explaining but I hope you get what I mean.