ing sounds means to distinguish two or more sounds that are in the neighboring position in terms of places of articulation. For most middle school students the discrimination of some sounds is a problem in listening comprehension. The reason that some students can’t understand the listening materials is that they can’t discriminate some voiced and voiceless consonants, short and long vowels clearly, such as [i][ ], [ ][ e ], [s][ ], [ r ][ l ], [ ][ ]. For example, they can hardly distinguish the words like “chip-cheap”, “bad-bed” and “sing-thing”. In a sentence like “she stands on the right of the door and services the boss”, when some students hear the word “right” “boss”, they will recognize them as “light” and “bus”. Also, there are some students who are affected by their dialect language can’t discriminate the phonemes [n] and [l], [s] and [ ] and will pronounce them mistakenly, which adds the difficulties of English listening training.
2.1.2 Liaison
Liaison occurs between two neighboring words in one sentence, if one word ends with a consonant, while the latter one begins with a vowel, these two phonemes are often pronounced together in the speed flow. Liaison in English is quite different from Chinese. In Chinese, there is no liaison. So liaison is a difficult and important point for the middle school students in learning English as well. And it is a key link in listening comprehension too. There are too many students cannot understand liaison, so if the students can’t master it well, it would become a vital barrier in listening. For example:
(1). What about you? [w t ' b ]
(2). Please put up your hands! [pl z pu t p j h nd]
(3). Can you repeat again? [k n ri ' p t ' g n]
Liaison is very common in English, if students aren’t familiar with liaison, when liaison occurs in the process of listening, students will be at a loss.
2.1.3 Incomplete plosive
“Loss of plosive is also an important factor affecting listening comprehension. Usually, a complete plosive occurs when two stop sounds are adjacent in a word or in a phrase, and incomplete plosive occurs when a stop sound precedes one of the fricative sounds or when a stop sound precedes one of affricate sounds.” [4] Loss of plosive is a common phonetic phenomenon in English. “If behind a plosive there is another plosive sound, the former plosive sound will not be plosive, just the vocal organ makes a pose to pronounce this sound, and then pronounce the latter one.”[5] For example:
(4). Next door [nekst_d ] (5). stop talking [st p 't ki ]
(6). Old friend [ ld frend ] (7). fast train [f st tr n ]
If students do not know this phonetic knowledge, they cannot understand the listening materials correctly; this would hinder their listening comprehension.
2.1.4 Word stress and sentence stress
The stressed and unstressed words are another important factor that affects English listening. It is frequently more difficult for the beginner to listen to and understand some speakers if they are not familiar with stress patterns. “The location of stress in English distinguishes meaning. A shift of stress may change the part of speech of a word from a noun to a verb although its spelling remains unchanged.”[6] For example:
(
