The use of microtones, or rather lack thereof, is what I'm referring to (from a comment by pythko):
>I believe the GGP meant to refer to “microtones,” which are frequencies that don’t fall into the Twelve Tone Equal Temperament tuning system. These are commonly used in non-western music (Indian music is a typical example), and occasionally in some western music styles (blues, some jazz, some sub-genres of rock, maybe), but you’re not going to find microtones in most western music.
>I believe the GGP meant to refer to “microtones,” which are frequencies that don’t fall into the Twelve Tone Equal Temperament tuning system. These are commonly used in non-western music (Indian music is a typical example), and occasionally in some western music styles (blues, some jazz, some sub-genres of rock, maybe), but you’re not going to find microtones in most western music.