I think it is the acoustic equivalent to the Clippy effect: Human voices tend to take up a substantial portion of our mental bandwidth, because it is not just a sound our brain has to recognize, but then it has to go and actually understand the words being said or sung.
Instrumental music tends to have - at least on me - the opposite effect, it occupies the parts of my mind that otherwise might distract me, leaving the parts doing the hard work alone.
I think it is the acoustic equivalent to the Clippy effect: Human voices tend to take up a substantial portion of our mental bandwidth, because it is not just a sound our brain has to recognize, but then it has to go and actually understand the words being said or sung.
Instrumental music tends to have - at least on me - the opposite effect, it occupies the parts of my mind that otherwise might distract me, leaving the parts doing the hard work alone.