§ 8 Dipthong Changes
German ‘au’ sometimes becomes ‘aa’ (in call), as in PG. ‘laafǝ’ (to walk) G. laufen; ‘glaabǝ’ (to believe) G. glauben; ‘kaafǝ’ (to buy) G. kaufen; ‘tsaam’ (bridle) G. zaum; ‘traam’ (dream) G. traum; ‘fraa’ (wife, woman) G. frau, PG. pl. ‘weiwǝr,’ because, as the German plural of frauen could not well make ‘fraaǝ,’ the plural of weib was preferred.
German ‘au’ remains in PG. ‘plaum’ (plum) G. pflaume; ‘daum’ (thumb); ‘haufǝ’ (heap); ‘saufǝ’ (to sup); ‘haus’ (house); ‘taub’ (dove) G. taube; ‘aus’ (out); ‘fauscht’ (fist).
German ‘au’ becomes ‘oo’ (Eng. floor) in PG. ‘groo’ (grey) an earlier form of G. grau; ‘bloo’ (blue) G. blau; and the name ‘Stauffer’ is sometimes pronounced ‘stoof’r.’
In the plural, ‘au’ becomes ‘ei,’ as in PG. ‘haus,’ pl. ‘heiser;’ ‘maus’ pl. ‘meis;’ ‘laus’ pl. ‘leis;’ ‘maul’ (mouth) pl. ‘meiler’ G. pl. mäuler; ‘gaul,’ pl. ‘geil,’ G. pl. gäule (horses); ‘sau’ (sow, hog), pl. ‘sei,’ G. pl. säue, sauen.
When ‘au’ has become ‘aa’ the German plural äu becomes ’ee,’ as in ‘beem’ (trees) G. bäume; ‘tseem’ (bridles) G. zäume.
‘Floo,’ G. floh (flea) pl. ‘flee’ for G. flöhe, is due to the fact that German long ö is replaced by ee.
German au is u in the earlier PG. ‘uf’ (up) G. auf, found in Swisserland and other localities; but ‘haus’ is not hūs, and ‘maul’ is not mūl as in Swiss.