
Sound change is usually assumed to be regular, which means that it is expected to apply mechanically whenever its structural conditions are met, irrespective of any non-phonological factors (such as the meaning of the words affected). On the other hand, sound changes can sometimes be sporadic, affecting only one particular word or a few words, wit...
Found on
http://en.wikipedia.org/wiki/Sound_change

(from the article `West Germanic languages`) ...German in the lowlands of the north from High German in the highlands of the south. When the Germanic tribes migrated into southern Germany during ... ...languages had what Grimm called an `aspirate` (Latin f, Greek ph, Sanskrit bh). In order to account for these correspondences ...
Found on
http://www.britannica.com/eb/a-z/s/129
No exact match found.