In the article Slówik & Doan (2021), we decided to use the British standard mainly because it is utilized in the HIU curriculum as well as for technical reasons because there is an extensive phonetic corpus focused on accent variation based on the recordings of BBC news that will enable us to conduct further research later on. According to Peter Roach (2006: p. 240), “the accent has been known for nearly a century as Received Pronunciation, or by its abbreviation, RP”.

With the help of Hancock (2003), Cunningham (2009) and Singer (2012), we selected 17 potential pronunciation issues (listed in Table 1) that we expected might cause problems for Vietnamese speakers of English. About a third of the issues were chosen as a “control group” based on Hancock’s observation that they constitute a problem for the majority of English learners even though judging from our own in-class experience and the works of Cunningham and Singer, we did not expect them to cause any problems to Vietnamese learners.

Every pronunciation issue was subsequently modelled into an experimental sentence. E.g. experimental sentence for issue No. 1.: Peter put his big bag on the purple table behind the blue PC; No. 16.: The English language course costs six hundred dollars. Finally, 100 first year students were asked to read the set of 17 experimental sentences while simultaneously being judged on the scale 1 - 5; 5 being the most fluent and correct while 1 the most erroneous. The assessment was carried out by the two authors of this article and the pronunciation issues were then categorized based on the extent they hinder comprehensibility of the speakers. Here we are going to address some of the most prominent ones that occurred most frequently and can cause the most problems with comprehension of the speakers.

Our target was to create a small sub-corpus of spoken South Vietnamese English. We managed to record 8 speakers for approximately 9 minutes each. The speakers were labelled by five capital letters. The first letter A-D stands for the order of speakers, after that SVE stands for Vietnamese English and the last letter F/M represents gender. All the speakers were selected among the students of the 1st year at the HIU English Department, 4 males and 4 females. The main criteria were the origin from the Ho Chi Minh City and good English reading fluency but with prominent Vietnamese accent.

The speakers were asked to read BBC news (each speaker about 1000 words) from the database of newsreaders used by many phonetic departments across the globe. We used texts labelled AMA and JLA (AMA-Alice Moss, JLA-Jackie Leonard). Each text comprised approximately 500 words. All recordings were captured using a recording device with 4 microphones allowing stereo recording, sampling frequency up to 48,000 Hz, MP3 (up to 640 kb)/WAV (16/32bit) format and a button to adjust sound input. The format WAV 16 bit and sampling frequency 32,000 Hz was set as default setting for all the recordings.

The recordings were transferred from the device on a computer and labelled according to the abbreviations of BBC presenters and gender of the speaker. Adobe Audition software was used to convert the recordings to mono and then they were subjected to the analysis in the phonetic software PRAAT and Forced Aligner. As the last step of data preparation, the work of Forced Aligner had to be manually checked in the PRAAT files.

Finally, we used PRAAT scripts as well as manual selection methods to localize specific instances of the pronunciation issues of South Vietnamese speakers of English that were previously identified based on the preliminary research and described in detail in Section 2.1. In order to do so, all sounds were annotated to Text Grids and segmented into lexemes and phonemes in two separate layers.

Among the consonant issues, we managed to identify the substandard pronunciation of /θ/ (see Figure 3), insufficient discrimination of /s/ x/ʃ/ (Figure 4) and consonant cluster simplification or their complete elision (Figure 5 and Figure 6).

In Figure 3, we can clearly see from both the spectrogram as well as the oscillogram that the speaker ASVEF pronounced the fricative /θ/ as an affricate [tʃ]. Alternatively, Vietnamese speakers can also pronounce it as [t^h] because [t^h] is a natural item in the inventory of Vietnamese consonants. As standard British English does not utilize the [t^h] sound, this issue so typical for Vietnamese speakers does not constitute a large problem in intelligibility and it only requires a short period of getting used to by the listener.

In Figure 4, the speaker BSVEF pronounced the word “situation” with an /s/ instead of /ʃ/ in the final syllabe. The sound /ʃ/ does not occur in standard Vietnamese and it is becoming a rarity in the Southern dialect as well. The sound /tʃ/, on the other hand, belongs to the consonant itinerary of the standard as well as Southern Vietnamese and therefore it is pronounced clearly in English as well. The inability to distinguish /s/ and /ʃ/ has been a frequent issue throughout our recorded materials.

Figure 5 illustrates elision or consonant cluster simplification when the speaker CSVEM pronounces the word “president” without the initial /p/ and final /t/. Speaker BSVEM in Figure 6 demonstrates the omission of a final /s/ consonant. This phenomenon leads to many grammar-related misunderstandings due to the fact that it affects the 3^rd person singular nouns, possessives, plurals and contractions. Therefore, it is often difficult to determine the nature of the error i.e. whether it is a matter of pronunciation or grammar. Consonant omission (especially /s/) and consonant cluster simplification are two features of (South) Vietnamese English that were prominent throughout our recorded material as well as during the reading sessions in stage 1.

Regarding vowels, most speakers displayed insufficient discrimination of /ɪ/ x /i:/, which is often connected to the issue of pronouncing closed syllables with rising intonation (see 3.3.), and a substandard pronunciation of the vowel /ʌ/ (Figure 7) with a significantly more open vowel as well as a clear rise in the vowel pitch. Vietnamese phonotactics only allows for two tones in syllables closed with plosives (rising and low), which leads to the interference into Vietnamese English and most of the closed syllables with final plosives or fricatives experience a significantly rising pitch often leading to the wrong assumption that the speaker is in fact posing a question.

In Figure 8, Speaker ASVEF pronounced the diphthong /eɪ/ without the final element hence it sounded like a single vowel /e/ with a longer duration. Vietnamese utilizes 3 diphthongs but they are all falling/centring (see Figure 2) and therefore the articulation of a rising diphthong constitutes a hindrance for Vietnamese speakers of English. Not being able to pronounce the final element of rising diphthongs can also be classified as one of the key features of (South) Vietnamese English pronunciation.

Figure 9 illustrates how pronunciation rules from Vietnamese manifest themselves in the Vietnamese English. As described in 2.1.3., Vietnamese open ngang and syllables closed with plosives or fricatives with rising sắc. This leads to the high pitch of the open syllables and rising pitch of the closed syllables in

syllables in borrowed words tend to be pronounced using the high flat tone (South) Vietnamese English. The word “speaking” is pronounced with a significant rise in pitch on the syllable “speak” that is very unnatural for native English. This phenomenon also leads to problems in proper distinction between /ɪ/ and /i:/ as the long vowel also tends to be higher in pitch (Roach, 2006).