Speech sound is produced by the vocal organs with functions of distinguishing meanings, so it is more than a natural substance. Speech sound is the most direct sign system to record thinking activities and is the acoustic form of communication.

The physical foundation of speech sound mainly includes pitch, sound intensity, sound length and timbre, which are also the four elements to make speech sound. Pitch is the frequency of sound waves, i.e. the vibration times in one second; sound intensity refers to the size of the swing of sound waves; sound length refers to the length of the vibration of sound waves and timbre means the character and the nature of sound.

The vocal organs and their activities of human beings are the physiological foundation of sound. It consists of three parts: (1) Respiratory organs including lung, trachea and bronchia. Lung is the center of respiratory organs and the dynamic basis to produce sound. (2) Larynx and vocal cords are vibrant carriers of articulation. (3) Oral cavity, pharynx and nasal cavity are the resonating cavities.

The relationship between the speech sound and its meaning were determined in the long-term language practice and this relationship shows the social nature of the speech sound.

We should give attentions to pronunciation, grammar and vocabulary when learning putonghua. The difference in Chinese is obviously manifested in pronunciation. Not only in different dialect regions but also in the same region, or even within one kind of dialect, is there obvious diversity. Pronunciation diversity is the main reason to cause troubles in communication. Therefore, the key point to learn putonghua is to study standard Chinese based on the Beijing dialect. And to learn well the pronunciation, you must learn by training your mouth and ears extensively.

Putonghua pronunciation includes two parts: articulation and standard pronunciation.

Proper articulation is the basic requirement in learning pronunciation. To articulate accurately is related to the ability to catch and distinguish sound correctly. Therefore, the ability of differentiating speech sound should be improved at first. After mastering how to pronounce properly, you should practice repeatedly to be perfect.

Standard pronunciation means to master standard putonghua and correct the non-standard pronunciation caused by dialect, which belongs to the memorial training. The difference between the dialect and putonghua is not totally irregular. After you learned their corresponding regularity, you would not have to memorize pronunciation one by one, but group by group. With the foundation of standard pronunciation, you can use them gradually in your daily oral language after enough practice of reading aloud and dialogue.

Scheme for the Chinese Phonetic Alphabet is formulated by the state for the Chinese phonetic alphabet and its spelling rules. It is a legal pinyin scheme of P.R.China and an international standard on spelling Chinese special words and expressions in world literature work. On February 11, 1958, Scheme for the Chinese Phonetic Alphabet was approved formally and ratified to issue on the fifth Commission of the first National People's Congress.

Scheme for the Chinese Phonetic Alphabet adopts universally used Latin letters and introduces in syllable-structured standard pronunciation based on Beijing dialect.

Scheme for the Chinese Phonetic Alphabet includes Alphabet, Shengmu List, Yunmu List and Intonation symbols. Alphabet regulates the shape, the name and the order of the 26 letters, and 25 of which can be used to spell all syllables in putonghua. Shengmu List and Yunmu List are drawn up according to the phonetic structure of putonghua, including 21 shengmu and 39 yunmu combined by 25 letters.

The main purpose of Scheme for the Chinese Phonetic Alphabet: Mark Chinese characters with phonetic alphabets and spell correctly putonghua. As a common base for the minorities to create and reform their own characters, it can also be used to process Chinese information, to transliterate foreign names, place names and scientific and technological terms, as well as to help foreigners learn Chinese.

Phoneme is the smallest unit in phonological analysis. It is classified into two types in terms of phonetic nature, that is Vowels (Mother sound) phoneme and Consonants (Child sound) phoneme.

The sound in the production of which air-stream passes through the oral cavity without obstruction but with the vibration of the vocal cords is called VOWELS. For instance, a, i, etc.

The sound in the production of which there is an obstruction to the air-stream as it passes through the oral cavity without vibration of the vocal cords except for some voiced consonants (m, n, ng, l, r) is called CONSONANTS. For example, b, p, etc.