"indistinct words" is correct and usable in written English, and can be used to refer to words that are not clearly heard or understood.
For example, "The phone line was so bad that I could only make out indistinct words".
The music (by Laibach) and somewhat indistinct spoken words (by Neil Armstrong and Gloria Steinem) also suggest turmoil.
The instinct to describe what were, necessarily, incredibly indistinct features with words with terrestrial connotations undoubtedly reinforced the sense that Mars was Earth's mirror.
The gradations can be as indistinct as the words heard in an insomniac's nightmare: Which is sleep and which waking, which is dreamt, which real?
The baritone Gary Lehman as Giorgio Germont sang with a rounded, deep-set tone that rendered some of his words indistinct, but he had the properly stiff rectitude to be Alfredo's troubled father.
And it sounds as if this band has inherited some of Deerhoof's anti-production too: Sam Scranton's bass drum like a tabloid headline; Aaron With's trebly guitar and dry-sounding vocals, mixed low enough to make the words indistinct; keyboards and electronics (from Mark Cartwright) used in nontraditional ways, sudden surges of ensemble sound that push everything into the red.
She demonstrated by tucking her chin and talking so softly that her words were indistinct.
(Internet versions of the same moment carried no such electronic fig leaf, but the words were indistinct anyhow).
As the dark draws in, they work away at O Come All Ye Faithful, with Malone gently ticking off the more experienced singers for overshadowing the others, complaining that some words are indistinct, and suggesting they harden "Lord".
The words were indistinct, but the music was like a transmission heard from far off in space -- little vocal jabs, sighs, murmurs and upward queries.
