五言詩發展到唐代完成了藝術形式上的律化工作，唐代詩人在大量創作與實踐之下完成了字句上平仄和諧的聲調配置，至此以後，這種原理與規範影響了歷代的近體詩創作。本文透過文獻探討，研究詩人當時是如何將文字聲音這種難以紀錄的感知現象具體化、系統化、規範化。因受篇幅限制，本文僅就四聲聲調的部份做初步探討，分別從四聲理論的繼承、樂調與聲調的比況、四聲的認識、及四聲的平仄分化，討論唐代近體詩在律化過程中，對於文學語言上聲調的具體概念與掌握。

The development of Five-word poetry completed the art form of Chinese classical regulated poetry in the Tang Dynasty. Poets who were in the Tang Dynasty completed tonal harmony and configuration of classical poetry by a lot of creation and practice. These principles and rules affected classical poetry in later generations. This essay is to study how poets specified, systematized and standardized the perception of sound which is so difficult to record. This essay contains four aspects. They are the antecedents of the theory of Four Tones, a comparison between tone of musical and tone of language, the cognition of Four Tones, and Ping-ze of Four Tones. This essay is to study the process of the regulation of Chinese classical poetry and the cognition of tone in literature in the Tang Dynasty.