c1=m1=t2, sound produced by the friction/contact/rubbing between m2 and m3, is a gride sound/hair-raising/sets one's teeth on edge/squicks/gives the willies/heebie-jeebies to t1, who hears it against background/noise t3.
This is epitomized by the sound of nails on a chalkboard. Short for seltinmosycpina. Cf. pecrufcpina.