John Samuel Kenyon, Thomas Albert Knott: A Pronouncing Dictionary of American English

More than ten years ago several scholars especially interested in American English suggested to one of the present editors the making of a phonetic pronouncing dictionary of the speech of the United States that might serve, both in the United States and elsewhere, the purposes served for Southern British English by Professor Daniel Jones's English Pronouncing Dictionary. About six years ago the editors became associated in this work.
Although as a pioneer in the field great credit must go to Professor Jones, who has placed all later lexicographers under inescapable obligation to him, our task is much different from his. He records the pronunciation of a limited and nearly homogeneous class of people in England in a type of speech identical with that of the editor himself. Our problem has been to record without prejudice or preference several different types of speech used by large bodies of educated and cultivated Americans in widely separated areas and with markedly different backgrounds of tradition and culture. Here let it be emphasized once for all that we have no prejudice whatever either for or against any of these varieties of American speech.