Arbitrariness: there is no natural relationship between the forms of linguistic signs and its meaning. 语言符号的形式与所表达的意思之间没有天然的联系。

Articulatory phonetics: the study of the production of speech sounds. 发音语音学，研究语音如何产生的。

Acoustic phonetics: the study of the physical properties of speech sounds. 声学语音学，对语音物理属性的研究。

Auditory phonetics: the study of the perception of speech sounds. 听觉语音学，对语音感知的研究。

=Perceptual phonetics

Applied linguistics: the application of linguistic theories and principles to language teaching, especially the teaching of foreign and second language. (narrow sense)

it refers to the study of language and other theories in relation to any language-related problems. 应用语言学，指对语言学及与任何语言问题相关的理论进行的研究。

Actual linguistic be