Is there any explanation as to why it sounds like Neelix was badly dubbed over for a single word in the Star Trek Voyager episode, Tuvix?

I've been rewatching Voyager on Amazon Prime, and have stumbled upon something ridiculously nitpicky, but is bothering me deeply. About 1:38 into the episode, "Tuvix," Neelix asks Tuvok, "Why don't we sing a song while we toil?" The word toil is significantly (demonically?) deeper than the rest of the line. It seems possible that the character is doing it playfully, but I can't effectively confirm it one way or another. Is that really Ethan Phillips saying the word toil, is it dubbed over, or is this version somehow degraded?

Edit: I've been so far unable to find the clip on youtube for comparison.