L1 INFLUENCE ON VIETNAMESE ACCENTED ENGLISH

‘Each variety of English in the world has its own distinctive features which are associated with various reasons. The research aims primarily at discovering whether L1 strongly influences Vietnamese accented English or not. In order to meet this aim, the research focuses on: (1) identifying phonological similarities and dissimilarities between Vietnamese and English vowels and consonants based on both acoustic and articulatory features; (2) investigating acoustic features of Vietnamese English vowels; (3) answering the question of whether the pronunciation of the speakers is influenced by the phonological differences and similarities. This research is of descriptive type and the method adopted is a mixture of qualitative and quantitative approach. Acoustic data are gleaned from 6 recordings made by six Vietnamese informants. The measurements of sounds are figured out by means of Wave-surfer program. The result of the study shows that Vietnamese accented English is strongly influenced by the dissimilarities between Vietnamese and English


Introduction
English has a great number of varieties in the world.Varieties of English in the Inner circle, Outer circle and Expanding circle are marked with their own particular linguistic characteristics.There have been a lot of research on varieties of English in the Inner and Outer circle such as Collins and Blair (2001), Crystal (2006), Cox (2005), etc., English is now unceasingly spreading all over the world and has become a 'global English' (Crystal: 2001).It is no longer restricted to countries where it is spoken as the first language, but a language of a diverse range of speech communities.English in the Expanding circle has gradually been paid attention to by linguists.'While non-native varieties of English have been recognized as distinctive varieties of English in the Outercircle countries, English in the Expanding circle has gradually becoming the focus of recent research from World Englishes perspective' (Ike: 2007).The term Vietnamese accented English has indeed been widely used within the past 10 years.It is a fact that English was played down during the time French and Russian dominated in most schools in Vietnam up to 15 years ago.Vietnamese English has hitherto developed over the course of 15 years.This short period of time is not long enough for the Vietnamese people to attain an equally proficient level but there is no doubt that Vietnam has really witnessed a very wide and dizzying spreading of English, especially in big cities of the country.The need to learn English is inevitable since English has become a 'Global language' (Crystal, 2001).Currently, English is an indispensable tool for Vietnam to enhance its national economics, to apply the world advancement in the field of science and technology and to bring forward the Vietnamese culture, traditions or other intangible values to the world.Following this trend, Vietnamese students are aware of the importance of learning English but they are encountering a lot of obstacles in finding jobs without acquiring a cer-tain English proficiency level set by employers.This implies that English learning is significant to the Vietnamese now.Due to the small scope of the study, the focus is merely on pronunciation aspects of Vietnamese English which is spoken by six ex-students of Hanoi University of Technology of Vietnam.The prime aim of the research is to discover L1 influence on Vietnamese accented English.In order to meet this aim, the research focuses on: (1) identifying phonological similarities and dissimilarities between Vietnamese and English vowels and consonants based on both acoustic and articulatory features; (2) investigating acoustic features of Vietnamese English vowels by analyzing vowels from six recordings; (3) answering the question of whether the pronunciation of the speakers is influenced by the phonological differences and similarities.By analyzing the speakers' pronunciation, acoustic features of vowels are identified and the speakers' errors in producing words are uncovered.Pronunciation errors are listed and divided into two groups.The first group deals with segmental errors including phonemic substitution, sound omission and addition, allophonic substitution and mispronunciation.The second group focuses on supra-segmental errors involving wrong stress position, equal stress placing and that is too weak.

Research Method
Error analysis is a new area to linguists in East Asian countries including Vietnam.In Vietnamese linguistic forums, hardly any works on errors analysis are found.On the contrary, it appears to be a field of great interest for Western linguists now.After CA works, Western linguists went on with behaviorist theory which was supposed to have important implications for second language acquisition; however, researchers quickly recognized the inadequacies of this theory.They found that second language learner data reflected errors that went beyond those in the surrounding speech and, impor-tantly beyond those in native languages.Errors analysis attracted researchers quickly.As Gass and Selinker (2005) assumed "errors provide evidence of a system, the evidence of the learner's knowledge of L2".With research on child language acquisition, it has been found that second language errors are not a reflection of faulty imitation.Rather, they are to be viewed as indications of a learner's attempt to figure out some system; that is, to impose regularity on the language the learner is exposed to.However, the concept of errors can be understood differently from learners and teachers' perspectives.Corder (1967) gave a distinction between mistakes and errors in which "mistakes are akin to slips of the tongue.The speaker who makes a mistake is able to recognize it as a mistake and correct it if necessary" whereas "an error is systematic.It is likely to occur repeatedly and is not recognized by the learner as an error".With this differentiation, there can be no errors in learner's systems, because a learner can mispronounce words, for example 'phonology' [f@"nol@ dZi] into [f@UnOnOri] without recognizing it as an error.The outstanding advantage of error analysis is that it provides more possible explanations to use to account for errors.
The study has tried to figure out the phonological differences between the two languages; acoustic features of Vietnamese English vowels as well as pronunciation errors to see how much the pronunciation of Vietnamese English vowels and consonants are influenced by Vietnamese language.For the first part of the study, phonological differences and similarities including phonemes (vowels, consonants) are brought forward.The data are then put into tables.The next part deals with primary acoustic data gleaned from six speakers' recordings, each of which consists of two sentences.Each recording is in turn looked into carefully, from word to word and sounds within each word.The measurements of vowel formants and length are done by means of a program called Wave-surfer.From formants f1 and f2, vowels are then plotted on a formant chart so that the positions of vowels are seen more clearly.In line with finding out acoustic data, errors are identified and classified into groups and then analyzed.Finally, based on the error types and the frequency of the errors, some pedagogical interventions are proposed.In the research, six graduate students (from Hanoi University of Technology (HUT)) were chosen for recording.

Comparisons of Vietnamese and English vowels and consonants
In order to address the first aim, a comparison is made between Vietnamese and English phonemes based on such aspects as the articulation, position and acoustic features of sounds.Vietnamese has two kinds of phonemes, the former consists of vowels and consonants, and the latter includes tones (sometimes referred to as tonemes).The research works on the first kind of phonemes.

Vowels differences
Vietnamese consists of 14 vowels (phonemes) including eleven monophthongs and three diphthongs.English has 20 vowels of which twelve are monophthongs and eight diphthongs respectively.The difference between Vietnamese and English in this case lies in the bigger number of vowels of English; English has five more diphthongs and one more monophthong than Vietnamese.Apart from that, the articulation of vowels themselves is differentiated.There exist sounds in Vietnamese which are not present in the English language.Several of the vowels of Vietnamese are typologically unusual to English.Thus, a point can be made here about the distinction between some similarly pronounced vowels.Learners of Vietnamese and English can be confused between [7] in Vietnamese and long or short [@] in English.At first hearing, they might sound the same, however, Vietnamese does not possess a concept of long or short [@] as in English and it is also not weakened or schwa in unstressed syllable as it is in English.In addition, for English or Vietnamese learners, [6] (<) and [V] sound quite similar.Nevertheless, as far as the height of the tongue is concerned, [a] is a low front vowel whereas [V] in English is in mid central position (Roach, 2003).In certain Vietnamese dialects [a] is the allophone or variant of [6] (a<) and [3] is the variant of [e].Monophthong [M] is normally considered new to foreign learners, so they find it hard to produce this sound.For the rest of the Vietnamese sounds, despite differences, they are not really too difficult to be pronounced correctly.
Vowels of the two languages are also distinguished in terms of vowel combination.Words in which the combination of these Vietnamese vowels occur are not found rare.The combinations are very common in Vietnamese but none of them is found in English.English also has its own method of vowel combinations, for example, that of one monophthong with a diphthongs like [aI{ ], [i@U], [ieI] and two diphthongs [@UeI] exist only in English.However, this kind of combination is not common.They can be seen as special cases of joining monophthong and diphthong.English has eight diphthongs which are classified into groups namely Centering and Closing.Three , 2003).In Vietnamese, more cases where vowels can go together to make up diphthongs are found (as in table 2.a).One point about Vietnamese vowels is that the correspondence between the orthography and pronunciation is somewhat complicated.In some cases, the same letter may represent several different sounds and different letters may represent the same sound.The letters 'y' and 'i' are mostly equivalent.There is no rule for when to use one or the other.

Vowel similarities
The similarities between English and Vietnamese vowels are based on acoustic data from the two languages.The measurement of Vietnamese vowels (spoken by a northern Vietnamese person) and British English vowels (spoken by a British person) is made.Despite the slight differences in data of sounds for the two languages, the sounds are produced in the same range as far as the formant F1 and F2 are concerned.Take vowel [i] as an example, F1 for Vietnamese [i] is 324 and for the English one is 367, this is not a big difference.The same is for F2 of vowel [i].And the rest of the six sounds also share the similar range of formants F1 and F2.The fact that vowels have the same range of F1 also means that they are produced with the same height of the tongue and the same range for F2 shows that they are made with the same frontness of the tongue.From the parameters, it can be concluded that these seven vowels are shared vowels between Vietnamese and English.The similarities are not merely displayed in numbers but also in how the sounds are produced.For example, vowel [i] in 'di'[di] (go) is produced with similar features with [i:] in 'see'[si:], it is a high, front, spread, long and tense vowel.Though there is no concept of long or short, tense or lax for vowels.
[i] at the end of a word in Vietnamese is longer than when it is in the middle of the words such as 'hit'[hit] ('inhale').And in this case, it is quite similar to [i:] in English.The same thing happens to the rest of the listed vowels.

Consonant differences
The number of Vietnamese consonants is 22 while English has 25 consonants.Nevertheless, there are ten consonants standing at the beginning of a word in Vietnamese whereas 15 consonants stand at the beginning of words in English.The consonants of the two languages are considerably different.For example, /z/ in Vietnamese is different to that in English when it is the Northern dialect of Vietnamese including the Hanoi dialect.When Southern and Central Vietnamese pronounce the sound, it is quite similar to [r] in English (a kind of retroflex).English has affricates [tS], [dZ] while Vietnamese does not have them.A lot of learners of Vietnamese pronounce the two sounds incorrectly.However, those coming from the Center and the South produce the first affricate correctly as they produce it like the two initial sounds in 'trÝi'[tS7i]('sky').Regarding nasal sounds, the difference is that English has [N] while Vietnamese has [l] (this is a Vietnamese nasal sound) as a nasal, but they share [m] and [n] as nasals.Vietnamese does not have approximants while English has [w], [j] as approximants, but Vietnamese has consonants produced with the tongue tip curved backwards and towards the back of the mouth, similar to retroflex [r] of English, for example 'tr' in tròn ('round'); and one sound similar to affricate [tS] of English, it is ["] in the word chay ('run').Some consonants appear initially only in Vietnamese such as [©] in nhÏ ('small') and [N] in ngu'('stupid') while in English they may appear at the end such as [] in sing [sIN].English also has consonants in initial position that Vietnamese does not have such as [w] in warm and aspirated [tŽ] in top [tŽOp].Presumably the hardest-pronounced consonants specific to English are [T] and [D] which are difficult not only for Vietnamese learners but also many foreign learners of English.English appears to possess a wider variety of more complex consonants and sound consequences across syllable positions.In English there are a lot of consonants that can stand at the end of a word whereas there are not so many in Vietnamese.This difference is illustrated in table 5 which shows that consonants or consonant clusters stand in numerous words in English whereas in Vietnamese this phenomenon is restricted to not many sounds.This is also a reason that causes Vietnamese learners of English to face a series of difficulties when producing these sounds.

Consonant similarities
In terms of manner of articulation, it can easily be seen that both languages have plosives, fricatives, laterals, nasals and a glottal.Vietnamese and English both possess plosives such as Vietnamese with [t, tŽ, p, c, k, b, d], English with [p, b, t, d, k, g]; fricatives such as [v, f, s, z] in Vietnamese and [f, s, z, h, v….] in English.This fact indicates that the biggest difference between the two languages is that Vietnamese lacks some consonants English possesses.This is one of the reasons why the Vietnamese learners of English mispronounce English words.Regarding voicing, English and Vietnamese both have pairs of voiced and voiceless consonants.There are 16 out of 18 consonants making pairs of voiced and voiceless sounds such as In the earlier part, it was noticed that English has a lot of consonant clusters in the final position whereas Vietnamese does not.Despite the difference, result reveals that there are consonants found in the final position of both Vietnamese and English.At initial position, shared consonants include [p, b, d, k, m,  n, f, v, s, z, h, l], [r] of the southern Vietnamese dialect, [s] and [z] of the northern Vietnamese dialect.However, noteworthy in this case is the lack of aspiration of [p] and [k] in Vietnamese.These sounds may easily be mistaken for [b] and [g] by English speakers of Vietnamese.In English, [p] and [k] are aspirated in initial position but it is not the same for Vietnamese.In final position, the shared sounds can be seen above, but it should be noted that [p], [t], [k] in Vietnamese are unreleased whereas they can be in English.In spite of similarities, there are multiple consonant sounds specific to each language, for example [T] is specific to Vietnamese, it is the dental aspirated as pronounced in 'tho'[t^Ž7](poem) or dental as in 'to'[to](big) while in English [t] is pronounced between the teeth known as dental or interdental.Another sound that should be noted is [X] in 'khuya'[Xua](late) and /G/ in 'gà'[Ga](chicken) of Vietnamese.These are hard-pronounced sounds to English speaking learners; they are produced with a continuous air stream as fricatives (Roach, 2003).The last sound noted is [s], in the southern dialect of Vietnamese.It is produced like [S] of English (Dinh and Nguyen, 1998) Based on the comparison on the two languages' materials, it is seen that Vietnamese and English are not very much similar in terms of its vowels and consonants.They are different in the nature, the articulation and position of sounds in words though they look similar in the orthography.However, it can not be denied that there exist some similarities in the position of certain sounds in a word, in six vowels that share similar positions in vowel space.

Pronunciation aspects of Vietnamese speakers of English 3.2.1 Acoustic features of Vietnamese English vowels
Two languages may have similar sound systems; however they vary significantly in physical characteristics "including both acoustic characteristics (e.g the pitch of sound) and articulatory characteristics (how widely the mouth is open in producing a sound)" (Odline, 1989:12).This is correct and acoustic characteristics are investigated in this case.
Regarding vowels formants, the data indicate that the six Vietnamese speakers (informants) pronounce English vowels at an unstable range of F1, F2 and F3.Take vowel [@] as an example, Formant of vowels ranges from 286 to 490 which means that the position of the vowels produced or the height of the tongue when the sounds are produced are different among students.The position of the sounds in the formant chart shows that Vietnamese [e] (high, central) is different in both the front-ness and the height of the tongue as compared with English [e] which is a mid, front vowels.This is the same with vowel sound [V].The average range of formant 1 is from 408 to 776 for F1 and from 939 to 1265 for F2.Vietnamese English [V] which is mid, central as plotted on the formant chart is much higher than English [V] (low, central).In speaker 4' pronunciation, [V] is seen in the position of a high central vowel, which is a surprising point.Vowel [u:] has F2 ranging from 1102 to 1833, which brings this sound to the position of a central vowel, not a back vowel as it should be.Vietnamese English [i] is produced in high front position by the six students, but [I] is made higher than [i:].For instance, speaker 3 produce [i:] with F1 of 592 whereas speaker 1's F1 for [I] is 292.Furthermore, Vietnamese English sound [a:] is made higher than the English vowel [a:]; the vowel chart shows that the tongue is in mid position while English [a:] is in low back position.This is the same with [O] which is higher than the English one.The outstanding feature of Vietnamese English vowels is that most of vowels are made with higher position of the tongue than British English ones.
In terms of the length of vowels, the numbers show that the speakers are aware of a distinction between [i:] and [I] though these two sounds are produced at different lengths.Informant 4 produced [i:] as the longest vowel (230ms) as compared to the rest vowels while [@], [V] are produced as the shortest vowels (42ms) by speaker 5 and speaker 6; and no Vietnamese English vowels are produced in low position.
From the data analyzed, Vietnamese English vowels [I], [@], [u:], [e] are similar to Vietnamese vowels in the height of the tongue.However, in terms of the front-ness of the tongue, they are different.The result indicates that there is an influence of native language on English language though speakers produce sounds which are not totally Vietnamese in some cases.They may produce an 'Interlanguage' which 'is composed of numerous elements, not the least of which are elements from the Native language and the target language' (Gass and Selinker, 2001:12).There are some vowel sounds which are similarly made to the Vietnamese sounds such as [i:], [@], [u:], [e].However, Vietnamese learners appear not to be able to distinguish the two vowel sounds.
[o] (in 'co' [ko] (Ms) in Vietnamese and 'so'[s@U] in English), [e] (chet ["et](die) in Vietnamese and 'said'[se] in English).Six speakers pronounce these sounds as one and same vowel.This is made clearer by data measured from the six speakers (table 7 above).All six speakers produce [e] with F1 ranging from 367 to 449 and F2 from 1551 to 2122, which are the very range for Vietnamese vowel [e].

Segmental and supra-segmental errors
of Vietnamese speakers of English Regarding segmental errors, the above errors are found in almost all the speakers' pronunciation.This shows that speakers are strongly influenced by their mother tongue-Vietnamese.Therefore, all sounds, including vowels are produced like their language phonemes.The clearest evidence can be taken for sounds of [e] (eì), [o] (oì), [7] (£), [a] (a) which exist just in Vietnamese but replace all similar sounds as [e], [O], [o], [V].At first these sounds look quite similar, however, when they are carefully produced, the difference is undeniable.For example, there is no [o] (oì) in English but there is [@U], these two sounds are different, [o] (oì) in Vietnamese is a monophthong and a mid back vowel whereas [@U] is a diphthong which slides from [@] as in 'about' [@"bAUt] towards [U] (Roach, 2003).Numerous ex-amples of these errors are found.
As far as errors in voicing are concerned, speakers' recordings indicate that there is no difference between voiced and voiceless consonants such as between [t] in 'cat ' and [d]  The opposition of fortis and lenis is very important in pronunciation of English.For example, the consonant [z] in the word 'house' [haus] as a noun is entirely different from [s] in 'house ' [hAuz] as a verb.In some cases, speakers do not even pronounce final consonants such as [t] in 'part ' [pa:(r) 'each' [i:tS].The second spectrogram shows that the word 'each' is just produced as [i:] without [tS] which makes a turbulence of sound if produced The habit of omitting final sounds in the mother tongue of Vietnamese speakers is in fact a negative point that inhibits the pronunciation of final consonants in English.In other word this is a phonotactic constraint in the Vietnamese language with very few consonants that are permissible in final consonants.It is not always easy for foreign listeners to understand what Vietnamese speakers say when all final sounds are omitted.
Together with omitting sounds, there are a lot of cases where students add sounds after a word.The spectrograms also show that a word is added after the word 'and', in this case the adding sound is 'mo' [m@].The word 'and' should end at 5.05ms, however, the speaker add one more word until 5.45ms.The speakers add sounds in many unpredicted words such as after the word 'ands ' [{nds], and 'ares' [a:s] which are grammatical words or functional words.'s' is also added to words like 'way' [weIs], or even after preposition 'in' [ins], or after the second syllable of the word 'phonetics' [fonestik] (see the spectrogram above).These are unpredicted errors though they are made by most speakers.
The last kind of segmental errors is sound redundancy in which [s] is added to many words for example to 'cut' [kVt], 'cot' [kOt], even after the second syllable of the word 'phonetics' [f@nestik].This error is not taken as seriously by Vietnamese learners of English.And this leads to miscommunication in many cases.There are more cases of error making such as between [tr] and [tS].However, these might be mild errors so learners do not notice them.
In reference to supra-segmental errors, stress is significantly important in English in recognizing the meaning, the function of words.Nevertheless, the Vietnamese speakers in this study have almost no ideas of stress.Only two out of six speakers can produce stress correctly.The rest put stress arbitrarily.For example, 'phonetics' should be stressed in the second syllable, but it is placed on the first syllable and some students put equal stress for all syllable in words such as 'remarkable', 'phonology', 'listening', 'talking'.Some put very weak stress on a stressed syllable such as in word 'remarkable', 'phonology'.This is greatly influenced by Vietnamese.There are no tones for each word, so they consider all words as without tones like those in L1.Stress in L2 is very important "since it affects syllables and the segments that constitute certain nouns and verbs such as 'COMbine ' and 'comBINE' (Odline, 1989:116).However, learners of English do not put stress on the required syllables.Moreover, some other aspects of connected speech are ignored by speakers.Take aspiration as an example, [t] should be fully aspirated in initial position stressed syllables; however, it is not aspirated at all by speakers of Vietnamese.Some students produce aspirated [t] at even at such environment as at the end of the words, for instance 'cat'[k{tŽ], 'fat'[f{tŽ]…Other problems found in the Vietnamese speakers' recordings are the lack of linking or liaison between a consonant and its neighboring vowels such as between 'produce and', 'part of'…and other co-articulatory effects.
Why speakers of Vietnamese make such errors is a big question not only for linguists but also for Vietnamese teachers of English.Nevertheless, as regards phonological differences, it can be affirmed that their pronunciation is greatly influenced by their mother tongue pronunciation.Only Vietnamese listeners can realize this because they can recognize their mother tongue sounds which do not exist in English.

Discussions
The problem may lie in the fact that the concept of final consonant and consonant clusters is quite new to Vietnamese speakers.Vietnamese does not have clusters in the coda.Students are also confused by [t] in 'act ' [{kt] and replace [t] by [tS] in 'act', [s] and [z] in 'think', so [T] is produced as [s].Students try to produce [t] correctly.However, they often end up with [s] instead as they force the air too hard through.[Z], [S], [tS], [tZ] can be a challenge to many Vietnamese speakers.Considering manner of articulation for these sounds, they are produced with an air-stream escaping through a narrow groove in the center of the tongue, then causing turbulence between the tongue and the alveolar ridge.Also in terms of manner of articulation, affricates are composed of a plosive plus a fricative; 'they are produced by keeping articulators in contact a little longer so that frication can be formed ' (Roach: 2003).However, speakers normally are not able to differentiate between aspiration and friction and produce them interchangeably which makes their speech hard to understand.Few learners can correctly produce these sounds, but it is a fact that not many Vietnamese speakers can be successful with these sounds.
The problems appear to be tougher when these sounds lie at the end of a word.The new concept here for learners is that they have to hold the tongue against the alveolar ridge for the air to pass through with some frication.This is really a hard thing not only for Vietnamese learners but for many foreign learners of English.Not only the ending sounds are omitted, but also medial sounds such as [l] in 'gentlemen ' [dZentlmn]…are omitted.This can frequently be found in many other words.The reason may be that speakers are not familiar with controlling the speech organs when the medial sounds should be made.The idea of pronouncing final sounds is completely new to learners as Vietnamese does not require speakers to produce present final sounds.The mispronunciation is made in many cases, to such words as 'cot' [k@ut], 'remarkable' [rimad@bo], 'act' [atS] etc.,.The idea of stress is also totally new to Vietnamese speakers.Vietnamese has six tones which distinguish words and these tones are put within words whether English has stress for words but stress is not indicated orthographically.The need to remember the stress position is probably a hard thing for Vietnamese speakers, However, they produce English words like Vietnamese words without tones.Listening to these sounds students make, listeners may not understand what they are saying at all, however, Vietnamese speakers can guess what they are saying as they are quite like Vietnamese words.These errors cause great difficulty in communication and make speakers' conversations in daily contexts fail to be intelligible.These are not only common errors for these six speakers but for almost all Vietnamese students.

Proposed solutions
From these facts about Vietnamese students' pronunciation errors, there should be some warnings for schools, universities about the big influence of the Vietnamese language on the English pronunciation of Vietnamese speakers so that they can find out methods to improve students' pronunciation.Pronunciation teaching is not only the responsibility of teachers at university level for English major students as it is now in Vietnam, but it is the responsibility of all teachers from the lowest level like primary school to the highest level like at university as well as of the students themselves.Teachers should raise students' awareness of the serious result of mispronunciation so that students have a serious attitude to pronunciation.And during classes teachers should motivate students to learn pronunciation by different pronunciation activities or schools should be equipped with more machines for students to drill their pronunciation practice, some kinds of programs for pronunciation practice and grading students' pronunciation should be installed in computers in labs to let students see their pronunciation errors and improvement.People from different socioeconomic categories have somewhat different pronunciation patterns.'And their pronunciation is to some extent divergent and in all cases, different groups of speakers maintain a distinctive identity to some extent through linguistics means, including their pronunciation' (Pennington, 1996:5).She also added that 'differences in phonology that signal differences in group identity are not only differences in overall voice quality, but also differences in the pronunciation of individual sounds'.
Following this idea, Vietnamese English has its own identity.However, this does not mean that Vietnamese speakers can produce sounds in their own way freely.There should be a standard for the correct pronunciation of sounds so that people from all over the world can understand each other without great difficulties.Then communication among people from every country is more intelligible.At Vietnamese education institutions, teacher should always remind students of the distinctive vowel sounds which look similar to those in mother tongue so that students can avoid making it as their native sounds, especially Vietnamese sounds that look similar to English like [e], [O], [a].When students are taught how to pronounce the sounds separately, teacher should clarify the difference in the pronunciation of that Vietnamese sounds and English sounds.Students have to bear in mind this difference and regularly practice pronouncing the sounds.Students should try to pronounce the sounds right from the beginning and remember the stress.Moreover, pronunciation should be introduced in grade 1 (primary school) and should be seriously paid attention to (only Grammar and vocabulary are considered important so far).The standard for good pronunciation should be set among all schools and the appropriate amount of pronunciation practice should be fixed per lesson.Students should be introduced some materials for improving their pronunciation; 'Speech solution' is a very useful CD for pronunciation practice; it is sold in many bookshops in Vietnam.Besides, pronunciation test should be held regularly; extra-curricula such as contest, games, songs, activities of pronunciation practice are also very useful for pronunciation teaching.Students who have language deficiency (who cannot produce certain sounds correctly such as [s], [l], [n] should not be allowed to follow teacher training program as these future teachers will create students with the same pronunciation mistakes.That is unacceptable in education, accordingly, teachers of English pronunciation should be well-qualified as they will teach generation after generation of students.They should be sent to English speaking countries to be trained in the field of pronunciation teaching.

Conclusion
Before the research was carried out, English and Vietnamese were expected to share a lot of similarities and there may not be too much difficulty for the Vietnamese learners to pursue English.However, the result of the contrasting between the two languages, the evidence of acoustic features of Vietnamese English sounds and the speakers' pronunciation errors reveal that the difference between the two languages as far as phonology is concerned is noticeable.This difference has a great influence on speakers' pronunciation such as the Vietnamese speakers omit final consonants, add sounds or produce words without stress.Additionally, they produce English sounds like sounds that exist in their mother tongue for both vowels and consonants.English in each country has its own features and the effectiveness of learning a foreign language like English depends on many factors.According to Mitchell and Myles (2004) ideas second language learning may depend on cognitive factors such as 'intelligence, language aptitude, language learning strategies and affective factors involving language attitudes, motivation, language anxiety and willingness to communicate.'From the research, it can not be denied that Vietnamese speakers are seriously influenced by their mother tongue phonological features.And another important thing that learners should bear in mind that is 'up to a certain proficiency standard, the fault which most severely impairs the communication process in EFL/ESOL learners is pronunciation, rather than vocabulary or grammar.Their arguments make pronunciation more important in improving the communicative competence of learners' (Hinofitis and Bailey, 1980: 124).So we can talk about the distinctive sounds of English, French, Vietnamese and other languages.In this sense, we can talk about pronunciation as the production and reception of sounds of speech.In addition, sound is significant because it is used to achieve meaning in contexts of use.Therefore, mastering the differences between two languages and the acoustic features of the learned language for learning a foreign language is of significant importance.If learners do not recognize the dif-Tang, Giang M. (2007) Cross-linguistics analysis of Vietnamese and English with implications for Vietnamese language acquisition and maintenance in the United States.
in 'hold' or [s] and [z] are both pronounced as [s].The speakers' spectrogram clearly shows their confusing between [z] and [s].The word 'think' [TiNk] should end with voiceless [k], however, their pitch contours show that the sound [k] is not made and the word stops at a nasal [N].If [k] is produced as a voiceless sound, then the speech contour should stop at about 18.42 Southeast Asian American Education and Advancement Volume 2. http:// 129.115.51.210/index.php/JSAAEA/article/viewFile/13/8,2007Yallop, C. (1995) English phonology, Sydney, NSW: Macquarie University,.Yule, George.(2006) The Study of Language.Cambridge: Cambridge University Press.