The circular, he wrote, paid particular attention to “the sounds heard in ‘join,’ ‘oil,’ ‘oyster,’ ‘third,’ ‘girl,’ ‘turn,’ and ‘lurch.’ ”
The school board said “that ‘oi’ was far too frequently rendered ‘er,’ and that ‘ir’ and ‘ur’ were far too often pronounced ‘oi.’” So the words “ ‘oil,’ ‘join,’ ‘oyster’ became ‘earl,’ ‘jern,’ ‘erster,’ while ‘third,’ ‘girl,’ ‘turn,’ and ‘lurch’ became ‘thoid,’ ‘goil,’ ‘toin,’ and ‘loich.’ ”
Apparently this speech pattern was still heard in the mid-20th century. In a 1940 article in the journal American Speech, entitled “‘Curl’ and ‘Coil’ in New York City,” the Columbia University linguist Allan Forbes Hubbell discussed this “oi”/“er” swapping and some of the myths associated with it.
“The diphthongal form, despite the efforts of the schools and despite the ridicule to which it has been subjected, is employed by a majority of New York’s seven-and-a-half millions,” Hubbell writes.
“I am inclined to believe that it was once general in this area, and it is today by no means confined to the level of uncultivated speech, but is often found in the speech of the educated, especially among older people.”