I've heard many people pronounce す, つ, く, and る as if く and る rhyme, す and つ rhyme, but not any other pair. It seems as if す is sometimes pronounced [sɨ] and く is pronounced [ku]. This doesn't seem to make sense though, since in many song lyrics they do rhyme and are used for rhyming effect.
Is this related to the fact that す and つ are often devoiced and the devoiced /u/ sounds like [ɨ]? Or is this related to the fact that my Chinese-accustomed ears mislead me when the う line is devoiced? This is especially since it seems like people who pronounce the vowels of す and く the farthest are speakers with a Chinese accent, like the singer Alan Dawa Dolma. I swear though that for some speakers of Japanese I hear, す does not seem to rhyme with く.