one of the more common harmony processes is "coronal harmony", which affects coronal fricatives, such as "s" and "sh". then, all coronal fricatives belong to the +anterior class ("s"-like sounds) or the -anterior class ("sh"-like sounds). such patterns are found in the dene (athabaskan) languages such as navajo (young and morgan 1987, mcdonough 2003), tahltan (shaw 1991), western apache, and in chumash on the california coast (applegate 1972, campbell 1997). in tahltan, shaw showed that coronal harmony affects three coronal fricatives, "s", "sh" and the interdental "th". the following examples are given by de reuse: in western apache, the verbal prefix "si-" is an alveolar fricative, as in the following forms: