As of a couple patches ago, I believe starting with the Marionette patch, Sabetha does not play her voice lines during her fight. She will do the intro voice lines when you meet her on the platform, but once the fight starts, she no longer does her fight lines, (Flame Wall "Burn! Burn!" for example). Oddly enough, she will however comment on "Knuckles" line but that is it during the fight.