For example, if a lyric contains “that you”, it ends up like “thatchoo”. One example of this I can think of is in Karma by Taylor Swift (I know, I know, but it’s one of the most popular songs I listen to). The line where she sings “Karma’s a relaxing thought/Aren’t you envious that for you it’s not?” sounds like “arentchoo”. It doesn’t happen every time but it seems to happen unless you’re consciously making an effort to not make that sound. An example of this is in Love Story where she sings “That you were Romeo/You were throwing pebbles”, and it sounds like if you were just talking to someone and said “that” and “you” separately.
I’m just wondering if this happens in other languages with different combinations of sounds? It probably happens with other sound combinations in English too, but this is the easiest example to think of.
It happens in mine with the same combination of sounds, a case of iotation. Many words which have a “ch” sound in them arose as contractions of “t-y” or “k-y”, which we write as “ć” and “č” respectively.