The phonetic symbol used in American English is called the KK phonetic symbol, while the phonetic symbol used in British English is called the Universal Phonetic Symbol.

One of the biggest differences in pronunciation between English and American English is their treatment of muddy vowels (schwa, e written upside down in phonetic symbols).

American English is a pinyin text, consisting of letters, and its pronunciation is represented by letters. There are 26 letters in American English, of which the letters a, e, i, o, and u are vowels, and the remaining 21 are consonants. The letter y is sometimes used as a vowel. Each letter can have one or more pronunciations. Therefore, American English has 50 phonemes. The written form of phonemes is a phonetic letter, that is, a phonetic symbol. A phonetic letter is a phonetic symbol, which represents a phoneme. .

American phonetic notation, also known as K.K. phonetic notation, is written by John S. Kenyon & Thomas A. Knott. The pronunciation symbols used in the pronunciation dictionary describing American English compiled by IPA (A Pronouncing Dictionary of American English 1944, 1953) are commonly known as KK phonetic symbols.

The symbols used are all from the International Phonetic Alphabet (IPA) mentioned earlier. Kenyon and Knott only intercepted the symbols suitable for American English, and added the unique children of American English. The sound became the K.K. phonetic symbol of American English. This is the most commonly used and authoritative set of phonetic notation. From then on, people used to call the standard pronunciation of American English the K.K. phonetic notation. In daily life, the KK phonetic symbol is regarded as the representative of the American phonetic symbol.

The K.K. phonetic alphabet is a type of International Phonetic Alphabet. Some people mistakenly believe that the International Phonetic Alphabet is the phonetic notation for British pronunciation, while K.K. is for American pronunciation. This statement makes the International Phonetic Symbol seem to be only used to mark British sounds; and the K.K. Phonetic Symbol is not considered the International Phonetic Symbol. Actually this is not correct. The International Phonetic Alphabet, as its name suggests, is designed to mark the pronunciations of various international languages. Many linguists make partial modifications to the International Phonetic Alphabet to mark the languages ??they study, so there are many types of International Phonetic Alphabets.

Although the K.K. phonetic symbol is a type of International Phonetic Symbol, it can only be used to mark American pronunciation.

Another British phonetician, A. C. Gimson (he is a student of Daniel Jones and a professor of phonetics at the University of London, UK), revised the dictionary pronunciation of British English (13th edition, 1977 ; 14th edition, 1988), making it more representative of actual pronunciation.

Reference materials: American phonetic symbols—Baidu Encyclopedia? British phonetic symbols—Baidu Encyclopedia