Four tones (Chinese)

The four tones of Chinese poetry and dialectology (simplified Chinese: 四声; traditional Chinese: 四聲; pinyin: sìshēng) are four traditional tone classes of Chinese words. They play an important role in Chinese poetry and in comparative studies of tonal development in the modern varieties of Chinese, both in traditional Chinese and in Western linguistics. They correspond to the phonology of Middle Chinese, and are named even or level (平 píng), rising (上 shǎng), departing (or going; 去 qù), and entering or checked (入 rù). (The last three are collectively referred to as oblique 仄 (zè), an important concept in poetic tone patterns.) Due to historic splits and mergers, none of the modern varieties of Chinese have the exact four tones of Middle Chinese, but they are noted in rhyming dictionaries.

According to the usual modern analysis, Early Middle Chinese had three phonemic tones in most syllables, but no tonal distinctions in checked syllables ending in the stop consonants /p/, /t/, /k/. In most circumstances, every syllable had its own tone; hence a multisyllabic word typically had a tone assigned to each syllable. (In modern varieties, the situation is sometimes more complicated. Although each syllable typically still has its own underlying tone in most dialects, some syllables in the speech of some varieties may have their tone modified into other tones or neutralized entirely, by a process known as tone sandhi.)