Nanjing, the capital city of Jiangsu Province, lies along the Yangzi River, and is noted for its wonderful landscape and splendid history. And Nanjing Dialect, prevailing in and around the city, has long been the official language of China. Nanjing Dialect belongs to the Jianghuai Mandarin. One of the most distinctive features of Nanjing Dialect is its checked syllable, or entering tone, the terminology in traditional Chinese phonology, which has merged into other tones in Mandarin but preserved in most southern dialects and Jin Dialect. Syllables with the entering tone in Nanjing Dialect end with a glottal stop. The study aims at discussing the differences of vowels in checked syllables and open syllables in the dialect.

1.2 Literature Review

Chao Y. R. in his book Study on Modern Wu Dialects initiated the study on Chinese dialects under the framework of linguistic theory. Chao (1929) identified five tones in Nanjing Dialect: Tone1-yinping (such as “衣” ), Tone2-yangping (such as “移”), Tone3-shangsheng (such as “椅”), Tone4-qusheng (such as “易”), Tone5-rusheng (such as “一”) respectively. Rusheng is the Chinese name for entering tone, and yingping, yangping, shangsheng, and qusheng are four open-syllable tones. Chao examined the pitch scale of the five tones: yinping (31), yangping (13), shangsheng (22˨), qusheng (44˧), and rusheng (5). Syllable with entering tone in Nanjing Dialect ends with a glottal stop ([ʔ] in IPA), which makes the laryngeal and mouth muscle tense and obstructs airflow in vocal tract. Chao (1929) also pointed out that the glottal effect only functions when the vowel is stressed in short sentences or produced alone, and in common case the entering tone is just short.

Glottal stop can be both initial and coda of a syllable. A glottal stop initial syllable has two characteristics: the rapidly increasing amplitude, reaching its peak in a short time, and plosive segment at the beginning of the syllable (Wu & Lin, 1989, p. 203). The glottal initial bilabial [ʔb] and apical [ʔd] are found in some southern dialects. Hombert (1978) examined the glottal stop coda, and found the glottal stop coda has significant influence on the vowel F0 and this impact can be observed by perception experiment. The [ʔ] coda causes the F0 rise, while [h] coda causes the F0 fall. Thus, the dropping of glottal stops [ʔ] may cause F0 of preceding vowels decreasing  in tone language. Glottal stops can also be observed by electroglottography (EGG) signal—the O/C ratio, which indicates glottis open and close. The glottal stop coda also causes the O/C lower than 1 in EGG test (Shen, 2010). Although Glottal sound [ʔ] is defined as a contrastive phoneme in phonetics, the glottal stop coda is more of a tone feature than a consonant in most Chinese dialects.

Sun (2003) concluded the characteristics of checked syllables in Nanjing Dialect are as following: high pitch, short duration, glottal stop, and muscular tension.

High pitch means the fundamental frequency of vowels of checked syllables are higher than that of open syllables. Short duration means the checked syllables are often short and do not go through any changes during the articulation process. And glottal stop is a typical feature of checked syllables, which is produced by obstructing airflow in the vocal tract. Muscular tension implies that when pronouncing the checked-syllable tone, the laryngeal and mouth muscular get tensed.

Experimental studies have confirmed some distinctive characteristics of this entering tone in Nanjing Dialect, and offered several other findings. The diminishing of glottal stop does not influence sound pitch; the pitch of entering tones is still the highest. The duration time of entering tone is relatively short, about 66% of open syllables (Song, 2003). In contrast, Shanghai Dialect has five  tones,  including  two  entering  tones,  duration  roughly  from  70  ms  to  120  ms,  and  three open-syllable tones, duration roughly from 240 ms to 270 ms (Zhu, 2005). So, in Shanghai Dialect the entering tones are more obviously shorter than open-syllable tones.