The only reason why she talks now is because of the old league lore, and they've been changing VAs and VOs lately. We've seen Bard be this voiceless sound guy, so will Sona play only music? Something like DJ Sona.
Sharjo7 votesGiven the fact that some of the champion quotes we get for new and VU'd champions are more like their thoughts than them saying anything aloud, we'd probably still hear her thoughts. I doubt they'd get rid of that.
I wonder if they'd actually do a little trick and make it so she actually thinks during her emotes (taunt, joke, laugh, etc) but you don't hear her unless you're playing her.
Celio Hogane HD1 votesBut sona already does that...
Sharjo1 votesNotice how I said "still hear her thoughts". I didn't imply anything would change other than in the event of a new VO for her she'd just get an expanded set of lines.
Peridition4 votesI don't see why she would be mute.
As Shario said, champion quotes (except taunts) appear to be random thoughts or inner monologue.
don't say anything, solely because they don't speak an recognizable language.
o0O Madoka O0o1 votesI would like to know the answer too.
The HeraId1 votesSona uses telepathy according to her old lore, and i doubt that will change, and I like the idea of thoughts.
You already have Sion which is basically him thinking about what he used to be, and his seemingly annoyed speech about hunger.
League is going away from the RTS of style of VOs, where everyone is speaking to you as the captain/general/commander of some sort.
Chromatic Eagle1 votesEveryone keeps saying these characters are thinking things instead of saying them out loud. I'm not sure if that's true. Sona only had telepathy because she was speaking to the summoner, and even then that seems more on the summoner than her on innate thoughts. Wouldn't he hear Bard or Gnar's thoughts more clearly if that were the case?
GreenLore1 votesThe reason why Bard&Rek'sai aren't understandable is becuase they THINK in a way that is completely alien to us.(and Gnar merely speaks a completely different language,same goes for certain lines of Yasuo and Karma,who sometimes speak an ancient ionian language) What you hear are their inner thoughts.
This is evident,because other players can't hear you unless you joke/laugh/taunt (and for certain champs dance or use certain abilities).Thats why sona doesn't say anything for her joke/taunt/laugh.
Sona however is just mute,there is no reason why her thought process would be different in any way. A deaf person on the other hand could actually get a kinda mute VO,because if you've been deaf your whole life,then you can't really know how words sound and thus your thought process won't really sound like you are just talking to yourself,if it would sound like anything at all.
Chromatic Eagle1 votesI'm really skeptical that Riot writes out a dozen move and attack lines if those sounds were just internal thoughts.
Sharjo1 votesWell for the attacks they'll like a collection of lines they might say if they were actually in a fight. Generally the VO for champions varies in terms of when they'd actually be saying it depending on the nature of the lines themselves. Some are them speaking to other people, some are them talking to themselves, and some are just thoughts. As an example let's look at Sion. Lines like:
"Another corpse for the pile." "Raise your weapon!" "My axe is getting cold!" "Your cries disgust me!"
Are among his lines used when he auto's something, and they're more like things he'd just yell in the faces of people. Coversely lines like:
"What am I?" "No...pain...no...feeling...but hunger..." "I hate this waiting."
Are among lines used when he just walks around and are more like him murmuring to himself.
GreenLore1 votesThen why can't anyone else hear them? Yet they hear you if you use certain abilities or let your champion laugh,taunt,etc.
Chromatic Eagle1 votesTo be honest, I never notice what the opponent hears or doesn't hear. They could be whispering to themselves too. Could also be a gameplay thing or else you'll be hearing a million voices too.
GreenLore1 votesThe thing is: there is pretty much nothing that indicates that these quotes aren't their inner thoughts,while there are plenty of reasons why they are likely just inner thoughts.I mean: -that others can't hear those quotes,but can hear your jokes,etc. -that this has been the case since the beginning and even with the removal of the summoners,there is nothing that indicates a change -it would be really weird if the champs would be constantly talking to themselves,thoughts on the other hand are pretty much always in your head.
Chromatic Eagle1 votesCan they hear attacks? Recalling? I don't think Riot pays that much attention to those distinctions, and I've already mentioned why gameplay could be the reason to not hear a million voices outside of taunts and jokes.
GreenLore1 votesCertain skills have hearable voiceover.
I think 
s ult for example and 
W and R.
Recalls are generally non-hearable.
AdanChristo1 voteswhat makes you think Sona is going to get re-worked?
Marcia1 votesSona got a visual update and rework already, it'd be weird if they didn't do any changes like you mentioned paired with those things. I think Riot usually tries to do stuff like that all together.
Chromatic Eagle1 votesI don't think they're happy with her rework since they keep nerfing her. Still trying to hit that invisible power.