What is the international phonetic symbol mentioned by the Chinese phonology teacher in class?

Phonetic symbols that record phonemes are called phonetic symbols. The most popular is the International Phonetic Alphabet. The International Phonetic Alphabet was formulated and put into use by the International Phonetic Alphabet Association in 1888. Its formulation principle is that "a phoneme is only represented by a phonetic symbol, and a phonetic symbol only represents a phoneme", and phonemes correspond to symbols one by one without confusion and ambiguity. Most of the symbols used in the International Phonetic Alphabet are Latin letters. When Latin letters are not enough, use Greek letters to supplement them. Sometimes, some letters are capitalized, reversed, linked or added with additional symbols to accurately mark the sounds of various languages in the world. In order to distinguish it from ordinary letters, symbols used in international phonetic symbols are usually placed in square brackets []. The pronunciation represented by the International Phonetic Alphabet is consistent all over the world, so don't confuse it with the pronunciation of letters with the same shape in a specific language. For example, the letter B of the Chinese Pinyin Scheme is written in the same way as the letter B of the International Phonetic Alphabet, but it represents different sounds. The first phonemes of English boy and book, the first phonemes of "run" and "companion" in Shanghai dialect are all [b], but there is no such sound in Beijing dialect. The letter B in the Chinese phonetic scheme is marked with the international phonetic symbol [P], the first phoneme of English speak, and the P in spring and the "Bi" and "Ba" in Shanghai dialect are also this [P]. In short, phonetic symbols are phonetic symbols, and letters are written symbols of words. When we see the symbols in [], we must distinguish them from letters with the same writing. For example, the word "fear" in Mandarin is written as "haàIPà" in pinyin and [xai5 1phA5 1] in international phonetic symbols.

There are FLASH courseware for learning international phonetic symbols on the teaching network for Chinese majors.