There's a bunch of guesses on how *h₁ *h₂ and *h₃ were pronounced in this Wikipedia page. They're usually defined by their effect in child languages though, so it's possible that some of those were actually multiple sounds.

For *h₃ you'll often see values like [ɣʷ] or [ʁʷ]; a labialised consonant (to explain why it often turns nearby vowels into [o] ) and voiced (as there are some claims that it voices nearby consonants, mostly Cowgill's Law)

My personal guess for *h₃ is completely heterodox, [ɸ]~[β]. I think that it's directly associated with *b being so uncommon in PIE.

[–] lars@lemmy.sdf.org 2 points 8 hours ago (1 children)

Happy Lemmiversary
I wish we could follow individual users because I could listen to you talk about PIE aitches for the next couple thousand years

[–] lvxferre@mander.xyz 2 points 7 hours ago* (last edited 7 hours ago)

Thank you! Sadly, I don't talk too much about PIE in Lemmy because... well, it's kind of a niche subject that most users don't care too much about.

Feel free to ask for further info on stuff, though. I do enjoy talking about it!

[–] smeg@feddit.uk 3 points 19 hours ago

Wow, that article is all proto-indo-european to me!

[–] fxomt@lemm.ee 7 points 1 day ago* (last edited 1 day ago) (1 children)

They're called Laryngeals, and no one really knows how to pronounce them, from what I can tell.

Edit, there are two theories on how to pronounce them:

Rasmussen chose a consonantal realization for *h₃ as a voiced labialized velar fricative [ɣʷ], with a syllabic allophone [ɵ], i.e. a close-mid central rounded vowel. Kümmel instead suggests [ʁ].

[–] CharlesMangione@lemmy.world 4 points 1 day ago

https://www.youtube.com/watch?v=Ccoj5lhLmSQ