> Bard "speaks" the way he does because, to ordinary beings or beings simply not worthy and cannot understand what Bard is saying because it might risk the future. The best way describing it is that Bard actually speaks the language the people of Runeterra are using, but his voice will sound distorted to other beings because they're not meant to understand him.
So who do you think can undertstand him?
Everyone, if he decides you're worth talking to.
...
No seriously, according to Riot if Bard was talking to you personally you'd garner what the hell he was saying. You probably wouldn't understand the sounds in a chime-word sense but you'd have an understanding of whatever point he was trying to convey to you just as well as if he had spoken perfect english/spanish/italian/shuriman/whatever.
On a more personal level though I'd imagine Soraka could understand him, considering their nature as being of a celestial nature, even if Bard's way less of a physical entity than Soraka.
: ♪♪♪♪♪♪
: what did you just call me?
Soraka is a good bet. She used to be divine, after all. There might even be a chance that she was his disciple, and lost her godlike powers because she interfered in human bussiness, something Bard is against.
Sona might understand him thanks to her musical predisposition and telepathic communication (What I assume is happening now that there's no such thing as a Summoner Link), or Bard's mind can be so above her it can jam her brain permanently.
Some of the other god-like beings might be able to communicate. The Ascended, Xerath, Tahm Kench, Aatrox...
Someone on a lot of LSD or shrooms.
People of Runeterra? Well void champions aren't people of Runeterra so I'm betting some of my money on them. The Overlord of the Void, who we don't know yet, probably could.
Telepathics might be able to understand bard.
Soraka could probably do it.
Any musician-scientist that can be bothered enough to decipher what each tone/pitch/timbre that he makes translates to. Maybe even Sona can understand or communicate similarly to Bard.
maybe 
The Meeps, for sure.
> Bard "speaks" the way he does because, to ordinary beings or beings simply not worthy and cannot understand what Bard is saying because it might risk the future. The best way describing it is that Bard actually speaks the language the people of Runeterra are using, but his voice will sound distorted to other beings because they're not meant to understand him.
So who do you think can undertstand him?
and
No one. His voice is literally like that because everyone is just too...insignificant...if that's the right word to describe it.
Only Station, The smartest mind in the entire universe could.
Aatrox and Tahm Kench are also possible...
