Ever notice that when a familiar song is playing in another room, you can clearly hear the words, but if unfamiliar, you can’t make out the words?
I’ve experienced something similar with self-recording musicians—especially voice-shy ones—who think they’ve set their vocal loud in a mix, but it’s barely audible to anyone else. This has happened to me with solo instruments as well (oboe parts, vocal harmonies, background guitar melodies, etc.).
Familiarity seems to result in experiencing more than is there, more than is actually making it through the walls and the noise—as if your brain, in order to finish constructing the mental content you (unconsciously) expect to experience, is pulling from memory the building materials your environment is failing to provide.
It turns out we can home in on and experiment with this phenomenon with a fascinating technique called sine-wave speech, which I first learned about it on the (excellent) Brain Science Podcast: Andy Clark on Prediction, Action, and the Embodied Mind (BSP 126; January 28, 2016). Listen to the first 2:15 minutes to hear a sine-wave speech demonstration (and I of course recommend the whole episode, especially if you’re interested in embodied cognition, a rising, and I think very promising, interdisciplinary field occupying philosophers, psychologists, linguists, AI-specialists, and others):