Because Sona cannot speak, these responses are understood to be magical telepathy with her summoner. This is seen in the fact that her external interactions (taunt, joke) are musical cues rather than words, meaning that, as stated, only her summoner can hear her words.
"Only you can hear me Summoner, what masterpiece shall we play today?"
"Order through music."
"Shall we resolve this dissonance?"
"The fanfare ascends."
"A symphony of justice."
"From my mind to yours."
"With perfect tempo."
"A sublime duet."
"Accurate, like a metronome."
"Accelerated movement, I concur."
Sona smacks her hands on her etwhal, points forward, and then gives a thumbs-down.
Sona plays different electric guitar sounds.
Sona plays a measure from "Deck the Halls" (Silent Night Sona)
Announcement made in the sneak peak by ByronicHero:
If you happen to be one of those people who is a sucker for musical types, you’ll be pleased to find out that we’ve got a musician waiting in the wings. Whether you’re longing for a melodious ballad or headed off to a headbanger’s ball, it’s likely that your heart will flutter as soon as you lay eyes on this little lady. Meet Sona, the Maven of the Strings. She’ll definitely tug at the old heart strings.
With PAX Prime around the corner, it seemed like the right time to celebrate the gamer in all of us. Arcade Sona offers an old-school gaming perspective on support with her arcade control panel (complete with joysticks), chiptune sound effects, and a colorful rainbow spectrum model. With her new arcade-inspired spell effects, including an ultimate that will make your enemies dance-dance, Arcade Sona will get you in the game.
Hymn of Valor: Sona plays the Hymn of Valor, granting nearby allied champions bonus Damage and Ability Power. Additionally, casting this ability sends out bolts of sound, dealing magic damage to the nearest two enemy champions or monsters.
Aria of Perseverance: Sona plays the Aria of Perseverance, granting nearby allied champions bonus Armor and Magic Resist. Additionally, casting this ability sends out healing melodies, healing Sona and a nearby wounded ally.
Song of Celerity: Sona plays the Song of Celerity, granting nearby allied champions bonus Movement Speed. Additionally, casting this ability energizes nearby allies with a burst of speed.
Crescendo (Ultimate): Sona plays her ultimate chord, forcing enemy champions to dance, taking magic damage over time.
Power Chord (Innate): After casting 3 spells, Sona's next attack deals bonus magic damage. Additionally, Sona's Auras persist for 3 seconds after deactivating and set off a 2 second global cooldown.