1． 结合毕业设计（论文）课题情况，根据所查阅的文献资料，每人撰写2000字左右的文献综述：

1. Introduction

Listening comprehension has played a significant role in second language acquisition because it is essential in communication. Meanwhile, our study and living environments are becoming more and more internationalized. We may encounter many foreigners with different accents in our work. Meanwhile, we may listen to materials with different difficulty levels. As a result, we want to explore the relations between accents and difficulty levels and English listening comprehension. In this study, we take American and British accents for example, which appear in our life most frequently. The aim of our research is to make our listening comprehension better.

1.1 Need for the study

In the process of listening research, we have found out many factors influence on listening comprehension. However, there is no clear-out answer to the relations between accents, difficulty levels and English listening comprehension. As a result, we conducted several experiments to search the relationship between accents, difficulty levels and listening comprehension so that we can apply into teaching.

In the past several decades, a lot of studies have been carried out to investigate accents and listening comprehension both at home and abroad (Li, 2009; Anderson, 1988; Zhang, 2001; Zhou, 2002), but much fewer studies have been conducted on the interrelationship between accents and listening comprehension (Barnwell,1971; Yao, 2011). More studies have been focused on the differences between English accents and American accents (Chen, 2001) and the characteristics of different accents (Zhou amp; Chen, 2008). Specifically, a lot of researchers have found out that quantitative and qualitative analyses of the effects of nonnative accents on listening comprehension. What#8217;s more, some thesis (Peng, 2012) discusses how to define different difficulty levels of listening materials. As a result, the research needs to be carried out at particular different accents that we often use during our study so that we could improve our listening comprehension accordingly.

In addition, this study should be undertaken because there is a bottle-neck on the improvement in our listening comprehension. Practice more and speaking more seem to fail in our improvement. Nowadays, in English teaching classroom, there is a dilemma, faced with the strong burden of examinations, a lot of teachers pay more attention to reading and writing parts in exams because they occupies most scores. As a result, listening comprehension has been ignored, not only owing to its low place in exams, but also lacking an excellent teaching way. Therefore, finding out the relationships between accents and difficulty levels and listening comprehension is necessary, which can help us find a good teaching way in listening comprehension.

1.2 Research purpose

The present study intends to investigate the effects of different accents and various difficulty levels on listening comprehension. Specifically speaking, the purpose of this study is three-folded. Firstly, whether there is any significant difference between British accent and American accent in listening, and whether this is any significant difference between easy and difficult materials in listening. Secondly, whether there is interaction of accents and difficulties in listening comprehension. Thirdly, to find out some way to improve our listening comprehension.

2. Literature review

Nowadays improving students#8217; listening comprehension has been the important goal in the college English teaching. As the main factors to affect on listening comprehension, accents play a significant role in nowadays English learning and teaching. As a result, the effects of British and American accents, materials of different difficulty levels, and the interaction of accents and difficulties on listening comprehension will be analyzed in this thesis. And in this thesis, literature is reviewed in three parts, first on the theoretical foundation，second on the empirical studies on accents and listening comprehension, and third on the problems in the previous study.

2.1 Theoretical foundations

2.1.1 The phonetic differences between British and American accents

The difference between British and American English that can affect us during listening comprehension is the speech. Therefore, the phonetic differences are of great significance in the research. Here are the differences we can learn from Oxford advanced English dictionary (Wehmeier, 2004, P.223-226).

2.1.1.1 Differences of the vowels

In British English, the vowel [a] is replaced by [aelig;] in American English. For example, the word ”dance”, in British English [dans], while in America English [daelig;ns]; ”bath”, [baoslash;] in British English and [baelig;oslash;] in America English; ”class”, [kla:s] in British English and [klaelig;s] in America English. Many such words in the sentence can easily occur due to the different pronunciation of the voice changes. For example: I can't do it. The pronunciation of ”can't” in American English, due to the role of the mouth, it is confused with ”can”. Listeners are not aware of this point and completely reversed the meaning of the word.

In British English, the vowel [o] substitutes [a] in American English. A short [o], in British English, only pronounces only for a long [o], and the American [o] sounds [a]. A long [o] sounds back if there is a [r].

One of the biggest differences between vowels deals with the Hun vowel (inverted[e] in Phonetic writing). In British English, voiced vowels frequently occur in the number of non-repetition of the short sound [a] (eg. ”about”) and the short sound [#1241;] (eg. ”computer”). [Er] in American English vowels rarely muddy, and sometimes short sound [I] (as sentimental, actuality), and [u] (eg. ”wust”), and even short sound of [oo] (eg: ”hooker”) adopted the muddy vowel.

2.1.1.2 Differences of the consonants

In American English, [r] in all cases should be pronounced, while in British English, [r] is generally not pronounced before a vowel. For example, the phrase ”clear animosity”, British English, will read separately, while American English would read wholly.

In American English, when [t] and [d] are caught in the middle of vowels, they pronounce with a slight vibration. Consonant [t] in American English is in pronunciation and sometimes very similar to the [d]. Such as ”writer”[#8217;raider] and ”rider” [#8217;raider], ”latter” [#8217;laelig;der] and ”ladder” ['laelig;der], sound is the same.

The two countries to handle the stress are quite different. British users are accustomed to the word's main stress on the various post-syllable, while American users will prefer to be placed in front of the main stress syllable. In many words ended in ”-ary” and ”-ory” and two-syllable words ended in ”-ate”, British English puts the main accent on the second syllable while American English puts the accent on the first syllable. For example,

Under normal circumstances, the second accent of British English is in front of the main stress, while the AE of the second accent appears in the back of the main stress, particularly, a compound word. For example,

Although the British English and American English slightly differ in pronunciation, it is easy to distinguish them, which does not result in learning difficulties in daily study.

2.1.2 The bottom-up and top-down processes

Two views of listening have dominated listening instruction over the last twenty years: the bottom-up processing view and the top-down interpretation view. The bottom-up process view supports that listening is a process of decoding the sounds from the smallest meaningful units ( phonemes) to complete texts. The process is finished in a linear fashion: the phonemic units are decoded and linked together to form words, which in turn from phrases; phrases are linked together to form utterances, which sequentially form complete meaningful texts (Nunan, 1997). Meaning itself is obtained as the last step in the process. Bottom-up view emphasizes the discrimination of input, because it is the start of the linear decoding. General bottom-up strategies in listening include listening for specific details, recognizing cognates, recognizing word-order patterns, and etc.

In contrast to the bottom-up processing view is the top－down interpretation view．It suggests that listeners , employing incoming sounds as clues, actively construct or reconstruct the original meaning of the speaker by utilizing background knowledge of the topic．The expectations activated by the background knowledge could assist listeners interpretation of what is heard and the prediction of w hat will come next (ibid)Top－down strategies take account of main idea comprehension, prediction, inference and so forth．

2.2 Related empirical studies on the relationship between accents and difficulty levels and listening comprehension

In one study regarding the effect of accent in listening comprehension, Loppez-Soto and Berrara-Pardo (2007) studied accent perceptions of Spanish EFL learners in two different accents of English, namely; General American, Received Pronunciation of British and found that 60% of the students found British English to be ”more correct” than American English.

The study above was conducted between only two accents, American and British. However, more related empirical studies were conducted between native accents and local accents and their results differ.

Smith and Bisazza (1982) conducted a complex international study, testing the comprehensibility of three varieties of English (American, Indian and Japanese) in seven countries, three ESL (Hong Kong, India, tme Philippines), three EFL (Japan, Taiwan, Thailand), and one native speaker (Hawaii). Their results were not as clear as in the above studies. In the two countries where both a native speaker and a local speaker were used (India and Japan) the result were dissimilar: in Japan the Japanese was best comprehended of the three speakers (with the American second, and the Indian the third);but in India the American was best comprehended ( with the Indian second and the Japanese third).

Another experiment was conducted in Hong Kong which was in line with the case of India in the Smith and Bisazza (1982) study, and found that native speakers, American and British, were more clearly comprehended than local Chinese speakers of English. Barlow, L. (2010), also provided evidence that there is no significant effect of accent on academic listening test scores for EFL students enrolled in a university foundations program at UAE University.

Major, Susan, Ferenc and Chandrika (2009) carried out an empirical study to explore the view that whether the listeners perform significantly better on a listening comprehension test when the speaker share their native language. The answer of it was not clearly yes or no. In this test, sometimes the native language listeners perform better than the non-native ones. Sometimes, it doesn#8217;t perform like this. As a result, there are many limitations in the experiment, which leads to the uncertain results.

Another experiment conducted by Wilcox (1978) found out that Singaporean learners of English found speakers of their own accent background easier to understand than speakers from different accent backgrounds. Similarly, in Brown#8217;s (1968) study in West Africa comparing Twi, Ewe, and British English Received Pronunciation, Twi and Ewe speakers understood English better when speakers shared their native language. Smith and Bisazza#8217;s (1982) research only partially supports this hypothesis: In their study, Japanese listeners more easily understood Japanese speakers of English than they did U.S. speakers, but, surprisingly, subcontinental Indians understood U.S. speakers better than they understood Indian speakers.

There are also many theses concerned with difficulty levels and English listening comprehension.

One experiment conducted by Zhang（2003）explored the impact of vocabulary and strength on English listening comprehension. He viewed vocabulary and strength as the two main factors to difficulty levels. It found out listening vocabulary size is more important to English listening comprehension than strength of listening vocabulary and there is significant difference between difficulty levels and listening comprehension.

Another study carried out by Qiu (2015) is about the relationship between difficulty levels and listening activities. She found out that there is significant difference between difficulty levels and listening comprehension and use this rule to design listening teaching.

2.3 Problems in the previous studies

Even if there are many references , many problems still exist.

The first problem is that most studies are qualitative instead of quantitative. Most studies only succeed to find that there are some significant differences on listening comprehension among different English accents. They fail to find out the clear-out relations and point out the solutions to overcome the barrier of accents and improve our listening comprehension. As a result, it is necessary to carry out more quantitative research.

The second problem is the result of the study. Although many studies were conducted, they haven#8217;t found an accurate result that is helpful to our study. There#8217;s neither clear result of accents influence on listening, nor the interaction of accents and difficulties on listening.

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