Conscious attention is a dynamic central process and is of value since it permits us to use salience criteria to ignore the extraneous while attending to the useful. Otherwise, too much is coming in to permit useful attention. I used to ask my students during a lecture (1) if their shoes were loose or tight and (2) whether they were aware of that before I asked. (There were always a few who responded to the first question with a "What?" They were attending to something other than the lecture.)
Yep. Conscious attention focuses attention on sensory inputs, certainly hearing among them. This is a classic that can also be demonstrated with the "reverse masking "nonsense. Play the reversed track w/o the words, maybe somebody might imagine a word or two. Show them the words, and the words are plain as day.
Lest anyone thing those words are really there, no, they aren't, they are purely the result of playing other (singing) speech backwards. Yes, a quick look at the waveforms prove this, too. The vocal track is a near-minimum-phase system, the ringing comes AFTER the glottal pulse. A quick look at the 'backwards masked speech' shows that it's not speech, it's REVERSED speech. When you listen to the unreversed speech, it's just stairway to heaven, like always.
You can do this with almost any reversed speech, if you like, imagine some words, write them down, listen for them. I don't have the track any more, but another guy at the labs, long ago, found "reversed masking" "twinkle twinkle little star" in some bit of a Mozart Opera. I regret not recalling the details.