I think having a thread for small questions (“What’s the IPA for this sound?”, “How do you write an affricate tie?”, etc.) that’s pinned and replaced every week or two would be good.
Just looking at new posts here in this community, i mostly see links to news articles and i don’t know if it would be appropriate to make a post for a small question with a simple but hard to find answer.
What makes a fricative sibilant? What’s the difference between sibilant and non-sibilant fricatives?
Sibilants are louder, specially in higher frequencies, because the obstruction of the airflow creates considerably more turbulence than for other fricatives. This is rather visible in spectrograms, like this:
See those dark (loud) bands at the top (higher pitch) for /s ʃ z ʒ/? It’s the turbulence.