The diphthong , as in "ow", is monophthongized to in some environments (sounding instead like "ah"), including before nasal consonants ("downtown" and "found" ), liquid consonants ("fowl", "hour") and obstruents ("house" , "out", "cloudy"). The monophthongization does not occur, however, in word-final positions ("how", "now"), and the diphthong then remains . That is one of the few features, if not the only one, restricted almost exclusively to western Pennsylvania in North America, but it can sometimes be found in other accents of the English-speaking world, such as Cockney and South African English. The sound may be the result of contact from Slavic languages during the early 20th century. Monopthongization also occurs for the sound , as in "eye", before liquid consonants, so that "tile" is pronounced ; "pile" is pronounced ; and "iron" is pronounced . That phenomenon allows "tire" to merge with the sound of "tar": .