[name]Thalia[/name] / [name]Talia[/name] – I am reading [name]Percy[/name] [name]Jackson[/name] and everywhere I look online seems to have different pronunciations.
[name]Tegan[/name] – does it rhyme with [name]Megan[/name] or is more like [name]Teagan[/name]?
[name]Aislinn[/name] – I’ve always said it like [name]Ashlynn[/name], but I have a student named this who says Osslynn.
In my opinion (or at least the way I’ve heard the names):
[name]Thalia[/name] = Tar-lee-ah
[name]Tegan[/name] = Tee-gen (with a neutral vowel in the ‘gen’)
[name]Aislinn[/name] = [name]Ashlin[/name]
[name]Thalia[/name] / [name]Talia[/name] - I always thought they were different; Tha-lee-ah, and Ta-lee-ah. I’ve also heard Tuh-lee-ah for [name]Talia[/name].
[name]Tegan[/name] - Tee-gen
[name]Aislinn[/name] - [name]Ash[/name]-lynn, pretty sure your student’s parents are saying it completely wrong. Likely didn’t research it.
[name]Thalia[/name] = thay-lee-ah (Greek name, I’m Greek)
[name]Talia[/name] = tahl-yuh/ta-lee-uh
[name]Tegan[/name] = I’m saying it like tee-gan
[name]Aislinn[/name] = It’s [name]Ashlyn[/name]
[name]Thalia[/name] - thay-lee-uh
[name]Talia[/name]- Tall-ee-uh
[name]Tegan[/name] -tee-gan
[name]Aislinn[/name] - ash-lyn though I hear this said wrong more often than not!
[name]Thalia[/name]-Tha-lie-ah (hebrew)
[name]Talia[/name]-[name]Tal[/name]-ee-ah
[name]Tegan[/name]-I think its Tee-gan
[name]Aislinn[/name]-[name]Ash[/name]-lyn
I like the name [name]Thalia[/name], so I was looking all over to figure out how to pronounce it as well!
[name]Thalia[/name] - [name]THAY[/name]-lee-uh (I’m just going with the Greek people on this one, and I like this pronunciation best)
[name]Talia[/name] - [name]TAH[/name]-lee-uh
[name]Tegan[/name] - I would probably say it like [name]Teagan[/name] (which this site lists as rhyming with [name]Megan[/name], whoops). I say [name]Teagan[/name] as TEE-ghin (g as in get) vs. [name]Megan[/name] as [name]MAY[/name]-ghin (g as in get)
[name]Aislinn[/name] - I also say [name]ASH[/name]-lyn
[name]Thalia[/name] / [name]Talia[/name] - [name]Tahl[/name]-yah
[name]Tegan[/name] - rhymes with [name]Megan[/name], megg-in
[name]Aislinn[/name] - ash-lynn
I went to school with a [name]Talia[/name] and she pronounced it “[name]Tal[/name]-yuh.”
In my head [name]Tegan[/name] sounds like “[name]Tea[/name]-gan.”
And I’ve never know how to properly pronounce [name]Aislinn[/name]! 
[name]Thalia[/name]/[name]Talia[/name] - [name]Tally[/name]-uh, though I’ve heard [name]Thalia[/name] said with the h pronounced as well, Thally-uh.
[name]Tegan[/name] - My Welsh housemate says it should be pronounced to rhyme with [name]Megan[/name] ([name]Meg[/name]-un). I have heard it said like Tee-gan as well, though I tend to associate that pronunciation more with [name]Teagan[/name].
[name]Aislinn[/name] - An Irish name, the Ais- sound is pronounced like [name]Ash[/name] in most British and American accents. Though if it’s said in an Irish accent, it is a bit more like the Oss-lin pronunciation.
I second all of these!
[name]Thalia[/name]/[name]Talia[/name]: I say TALL-ee-uh, but my best friend who is obsessed with [name]Percy[/name] [name]Jackson[/name] says [name]Thalia[/name] like THALL-ee-uh
[name]Tegan[/name]: I say it rhyming with [name]Teagan[/name]
[name]Aislin[/name]: I tend to say [name]Ash[/name]-lin, but I’m not 100% positive on the actual pronunciation
I pronounce [name]Talia[/name] the Hebrew way - tahl-ya, 2 syllables. I know a lot more Jewish Talias than I do Greek ones.
My Aussie husband insists [name]Tegan[/name] is teeee-gan but he also insists [name]Megan[/name] is meeee-gan and not meg-gin. I’d trust the Welsh over the Aussies. LOL.