1 Introduction

Students have demonstrated a growing interest in mobile learning and in the utilization of mobile devices for the purposes of English language learning (Dashtestani, 2016). Mobile learning can be referred to as an extension of e-learning that is realized via portable and wireless devices, providing learning anytime and anywhere on the basis of learners’ preferences and convenience (Kumar & Goundar, 2023; Kumar & Sharma, 2020; Traxler & Crompton, 2015). It involves teaching and learning through mobile technologies such as smartphones or tablet devices that provide users with the Internet access, including additional capabilities such as touch screens, cameras, downloadable apps, and location awareness (Fulantelli et al., 2015; Schuler et al., 2012). Mobile devices are often considered to be tools that have democratized access to technology since learners have in their hands more mobile devices in comparison to other types of gadgets, and these tools may be employed for the purposes of education, in particular within EFL teaching and learning (Hockly & Dudeney, 2018).

Kukulska-Hulme (2009) maintained that because of the popularity of m-learning in the field of second language acquisition, mobile-assisted language learning (MALL) emerged as an independent research domain. It is apparent that MALL provides learners with new, appealing, and exciting ways of language learning, offering major advantages in terms of foreign language education. “Key characteristics of mobile devices include among other things increasing portability, functionality, multimedia convergence, ubiquity, personal ownership, social interactivity, context sensitivity, location awareness, connectivity and personalization” (Cook, 2010, p. 2). According to Zaki and Yunus (2015), the following features may be beneficial to language learners: mobility, ubiquity, wireless connection, interactivity, availability, and privacy.

Mall can also be utilized for the following purposes (Arvantis & Krystalli, 2021; Karsenti et al., 2013; Kukulska-Hulme, 2009):

  • increasing motivation for learning through technology that students are familiar with (e.g., smartphones or tablets);

  • providing further opportunities to develop communication skills;

  • promoting the use of L2 as a unique way of communicating;

  • facilitating the teaching and learning process by investigating, analyzing, discovering, and selecting activities that are reasonable;

  • enhancing and reinforcing interaction between real and virtual settings, learners in the same classroom and other classrooms, within and beyond school boundaries;

  • encouraging learning in a pleasing way.

On the other hand, it should be noted that implementing mobile technologies into the teaching and learning process appears to be a challenging task since there are a variety of factors impeding the adoption of m-learning, e.g., technical, cultural, and learner-centered factors (Bidin & Ziden, 2013; Kumar & Chand, 2019). Therefore, its adoption can be regarded as rather slow. In connection with this, m-learning is mostly self-directed (mobile learning facilitates self-directed learning) and is influenced by a number of factors (Karimi, 2016). Further, there are few successful examples which have completely utilized mobile learning capabilities (Bidin & Ziden, 2013; Karimi, 2016; Kumar & Chand, 2019). However, it should be noted that research on mobile learning is still in its early development (Almasri, 2016; Al-Rahmi et al., 2021; Alsharafat, 2021), and its theoretical foundation has not matured yet (Kumar & Chand, 2019). For example, several issues are raised when implementing the concept of mobile learning into the process of language learning, such as problems with multitasking, Internet connection, small screen size, choice of appropriate apps, distraction from learning, and the state of (un)preparedness of both teachers and students (Chen & Yan, 2016; Heil et al., 2016; Klimova, 2019; Metruk, 2022). Other authors draw attention to different challenges, such as creating a gap between technically sound students and their less technically equipped peers, high dependence on network resources, or the possibility of feeling isolated from teachers and other learners (Asabere, 2013; Chandhok & Babbar, 2011).

It should also be pointed out that the majority of studies regarding mobile learning and language development have concentrated on vocabulary (e.g., Bensalem, 2018; Bieńkowska et al., 2021; Dağdeler et al., 2020; Kassem, 2018; Perwita et al., 2021; Shahbaz & Khan, 2017) or grammar (Ghorbani & Ebadi, 2020; Kashanizadeh & Shahrokhi, 2021; Khodabandeh et al., 2017; Rozina, et al., 2017; Sabahi & Rabbani Yekta, 2019), while research on pronunciation in relation to MALL is rather scarce (Ghounane & Rabahi, 2021; Saran et al., 2009; Shirmardi et al., 2021). This possibly results from the fact that pronunciation instruction has always been somewhat neglected (Bajorek, 2017; Nadia, 2017; Pardede, 2018; Seyedabadi et al., 2015) when compared to other language skills and systems.

Therefore, this study attempts to conduct a systematic literature review, which is, to the best of our knowledge, the first systematic review on pronunciation instruction in relation to mobile learning. The primary contribution of this review is the identification of studies that provide empirical evidence related to the use of mobile devices for pronunciation practice and development.

2 Prior work

Although research on m-learning focusing on pronunciation acquisition lags behind research papers conducted on grammar or lexis, some studies have attempted to examine the effect of m-learning or MALL on pronunciation of EFL learners. Arashnia and Shahrokhi (2016) aimed to investigate whether using mobile phones on EFL Iranian students is effective. The results demonstrated that the experimental group performed more successfully than the control group, indicating that EFL learners may learn pronunciation in an effective manner when they receive instruction through mobile phones. The study conducted by Kim and Kwon (2012, p. 31) “concludes that the ESL apps seem effective in that they provide a personal and learner-centered learning opportunity with ubiquitously accessible and flexible practices”. **g’s (2017) experiment, during which phonetics teaching was combined with mobile learning, also supported the notion that m-learning has a beneficial influence on phonetics instruction. In connection with this, it was also Walesiak (2017) who was in favor of mobile learning, claiming:

Whether you teach pronunciation as a separate skill or simply integrate it spontaneously into your lessons, mobile apps can definitely help you create a stimulating classroom environment, improve the quality and effectiveness of your teaching and reinforce to students the need to learn pronunciation. (p. 16).

Amalia (2020) also attempted to investigate the effectiveness of employing MALL in teaching pronunciation at a secondary school. The research results indicated that the mobile-assisted language learning brought about a significant effect on increasing the level of learners’ pronunciation ability. In addition to this, Retnomurti et al. (2019) described in their study an Android Table Program PROTADROID whose purpose was to facilitate pronunciation practice of EFL learners in Jakarta, Indonesia. It was established that learners who displayed positive attitudes towards the app generally understood and demonstrated capability for operating this program with a keen interest.

However, employing mobile technologies for the purposes of pronunciation instruction is not always straightforward and without complications, as a number of scholars have underpinned its effectiveness in terms of pedagogical interventions (Lan, 2022). There exists substantial controversy regarding how much attention ought to be devoted to technology while teaching pronunciation (Henderson et al, 2012). Most mobile learning pronunciation courses and applications do not seem to be pedagogically driven, as they do not offer clear instructional goals and adequate learner support, which results in learners experiencing out-of-the-classroom difficulties (Colpaert, 2006). Furthermore, Kukulska-Hulme (2005) maintained that a high number of mobile apps were not explicitly designed for pronunciation instruction; thus, teachers need to carefully and accordingly select mobile apps to meet the course objectives (Stockwell, 2010). Mobile courses do not always succeed in achieving learning efficiency without a well-structured mobile-mediated design of a pronunciation course (Kukulska-Hulme & Shield, 2008). It was also Aratusa et al. (2022) who, apart from identifying a positive perception of MALL in the teaching and learning process, found out that there also existed some difficulties in this regard, such as smartphone performance, redirections of students, and learners’ familiarity with the exploitation of phones for language learning purposes. It is therefore, important that there is an effective pedagogical intervention within pronunciation courses and their design to demonstrate the positive influence of mobile learning on pronunciation instruction.

Although innovative technology tends to stand out in a crowd and may even temporarily veil pedagogic falsity, EFL pronunciation instructors planning to employ MAPT must take into account the design of an effective pedagogical approach to facilitate interactive and collaborative learning in pronunciation and in turn achieve successful learning outcome. (Lan, 2022, p. 1562-1563).

There is no doubt that in spite of numerous advantages of employing mobile learning for pronunciation learning purposes, there are areas which merit further exploration so that mobile devices are exploited accordingly and effectively.

3 Research method

The methodological approach of this literature review is considered as the systematic literature review, which can be regarded as an essential tool for summarizing evidence in an accurate and reliable manner. A systematic review attempts to collect empirical evidence that is relevant to predefined eligibility criteria to precisely answer the formulated research questions (Moher et al., 2009). This review is based on PRISMA 2020, which is an updated guideline of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement published in 2009 (Page et al., 2021).

A review protocol was established, including identifying the data source, search strategy along with query strings, and inclusion/exclusion criteria. The primary source for the systematic literature review was one of the largest bibliographic databases, Web of Science (Ruggieri et al., 2021), which offers access to the world’s leading scholarly literature (Hugar, 2019) in all disciplinary fields.

The aim of this review is to examine, summarize and characterize the use of mobile devices for the purposes of pronunciation practice and learning. To obtain this kind of information, the following research questions were proposed:

  1. 1.

    What is the effect of mobile devices on pronunciation acquisition?

  2. 2.

    What are learners’ attitudes toward employing mobile learning for pronunciation practice and development?

  3. 3.

    Which mobile devices are applied in the articles and which pronunciation apps are employed?

3.1 Search strategy and query strings

Search strings ought to cover as much ground as possible while being sound in their size (Schardt et al., 2007). The query strings, which arose out of the previously formulated research questions, in the WoS database (all editions of the Web of Science Core Collection) within the field “Topic” were “mobile” OR “cell” OR “cellular” OR “portable” OR “mobile-assisted” OR “mobile assisted” OR “mobile-based” OR “mobile based” OR “m-learning” OR “smartphone” OR “smart-phone” OR “mobile device” OR “smartphone-assisted” OR “smartphone assisted” OR “smartphone based” OR “smartphone enhanced” OR “smartphone-enhanced” OR “MALL” OR “MALU” OR “SPALL” OR “SALL” OR “MAPT”. The second row (FIELD = TOPIC), which was combined with the first query row using the “AND” operator, contained the string “pronunciation” AND “accent”. The third row (FIELD = TOPIC) also employed the “AND” operator, containing the following terms: “practice” OR “training” OR “instruction” OR “learning” OR “teaching” OR “acquisition” OR “exercise” OR “drill” (Table 1).

Table 1 Search strings
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3.2 Inclusion and exclusion criteria

To evaluate the selected articles, the inclusion and exclusion criteria were defined. Only those articles that met the criteria in Table 2 were accepted for the purposes of this systematic literature review.

Table 2 Inclusion and exclusion criteria
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The initial search resulted in 300 articles. After applying all the limits (document type, publication years, language of article, Web of Science categories), the final number of records for screening was 74. The next step was to screen the titles and abstracts for articles relevant to the topic of this review. After careful evaluation of the 74 records, 42 articles were excluded for the following reasons: not relevant to the research questions (33 records), focused on a system or skill other than pronunciation (3 records), wrong sample (3 records), not an empirical study (2 records), and retracted article (1 record). This accounted for the total of 25 records sought for retrieval. The next step was locating the article full texts; it was not possible to find 7 full text articles, which means that the number of articles assessed for eligibility was 25. After reading the full texts of every article, 10 articles were excluded because of the following: not relevant to the research questions or outcomes (6 articles), wrong intervention (3 articles), and wrong population (1 article), resulting in a total of 15 studies included in the review (Fig. 1).

Fig. 1
figure 1

PRISMA flow chart on paper identification, screening, eligibility assessments and inclusion. **If automation tools were used, indicate how many records were excluded by a human and how many were excluded by automation tools

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4 Results

This section contains an in-depth analysis of the collected outcomes. The three research questions are answered, followed by the results interpretation and summary. Figure 2 displays which countries the empirical studies took place in, and Table 3 presents an overview of the studies.

Fig. 2
figure 2

Countries involved

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Table 3 Overview of the studies
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4.1 The effect of mobile devices on pronunciation acquisition

The primary objective of this systematic literature review is to examine and evaluate the effect of portable mobile devices on pronunciation development. Three studies did not mention the influence of mobile devices on pronunciation, but all of the remaining thirteen studies confirm the positive impact of mobile technology on EFL learners’ pronunciation. While some studies have revealed the usability of MALL in pronunciation learning (Ghounane, 2019) or statistically insignificant differences in learners’ sound perception and production (Fouz-Gonzáles, 2020), the majority of reports suggest that there exists a positive effect on the pronunciation of EFL learners, which is also substantiated by calculating statistically significant figures. For example, Lan (2022) aimed to investigate the effects of mobile-assisted pronunciation training (MAPT) on EFL students’ pronunciation performance as compared to computer-assisted pronunciation training (CAPT) instruction. “The statistical results of research question one attested that the MAPT students had not only achieved significant improvements after the treatment, but more importantly, had outperformed the CAPT students on the posttest” (Lan, 2022, p. 1579). Furthermore, the mobile app involved (English Pronunciation Tutor) proved to be an effective app, and most students suggested that they were satisfied and highly motivated when using the app, as it offered instructional videos, authentic material, and interactive learning environments. Alternatively, Khalil (2022) explored the impact of a pronunciation app (English Pronunciation, designed by HEPHAM) on nonnative Saudi EFL students. A statistically significant difference in the students’ performance before and after using the application was identified, indicating its positive effect. Another study concentrated on the effectiveness of m-learning on develo** English phonetic competence of prospective interpreters. “From the results, it is clear that usage of m-learning increases the knowledge of terminology and ability to product and percept English speech easily” (Gurova et al., 2020, p. 71). Therefore, it can be concluded that overall, the effect of mobile devices is positive and beneficial to EFL learners regarding their pronunciation acquisition. However, it should be also emphasized that further exploration in this area must be conducted.

4.2 Learners’ attitudes toward m-learning

Most of the reviewed studies have demonstrated positive attitudes of EFL learners toward the implementation of m-learning for the purposes of pronunciation acquisition, while three studies did not involve discussing attitudes in this regard. Mobile-assisted language learning seems to represent an important motivational factor in pronunciation development, providing learners with exciting ways of L2 learning and offering major advantages in terms of foreign language education.

Tejedor-García et al. (2020) investigated a novel learning game for the purposes of L2 pronunciation training in which players are challenged with each other. “The integration of automatic speech recognition (ASR) and text-to-speech (TTS) technology allowed users to improve their pronunciation while being immersed in a highly motivational game” (Tejedor-García et al., 2020, p. 74250). Alternatively, Chen’s study (2022) aimed to examine the potential of adopting speech-to-text recognition (STR) technology EFL oral training at the university level. Apart from recognizing the app’s effectiveness, the research participants also demonstrated positive attitudes toward the tasks in the app.

These findings appear to be in line with the fact that EFL learners generally express positive attitudes toward integrating MALL into the process of L2 learning (e.g., Botero, et al., 2018; Saidouni & Bahloul, 2016; Tra, 2020).

4.3 Types of mobile devices and apps/platforms involved in the studies

MALL can be defined as the use of “mobile technologies in language learning, especially in situations where device portability offers specific advantages” (Kukulska-Hulme, 2013, p. 3701). To better understand the utilization of MALL for the purposes of language learning, this review article also attempts to identify which mobile devices have been used most. While some studies did not explicitly mention the device involved (e.g., Tejedor-Garcia et al., 2020; Yang, 2022; Chen, 2022), it seems that smartphones were the most frequently used mobile devices in the studies (e.g., Cerezo et al., 2019; Lan, 2022; Akkara et al., 2020). Other studies involved both smartphones and other devices, such as laptops or iPads (Jiang et al., 2022; Kan & Tang, 2020; Yurieva et al., 2021, p. 93). However, smartphones were the most prevalent ones, being at the center of attention regarding MALL due to their availability, popularity, and computer-like functionality – features that enable the users to install third-party apps into the device (Horvath et al., 2020; Kim et al., 2014; Mindog, 2016).

Pronunciation apps are illustrated in Table 3. It is apparent that a variety of apps can be utilized for pronunciation practice. On the one hand, this fact is to learners’ advantage, and they can experience and enjoy all the benefits apps offer, such as ubiquity, portability, opportunity to share language work with their peers, and chance to practice all the language skills and systems. (Hossain, 2018). On the other hand, there also exist some challenges that must be confronted by both EFL teachers and students. App developers are working around the clock, the number of apps on the market is substantial, and learners might experience difficulties in selecting the most appropriate and relevant apps to tailor their needs. Furthermore, functionality apps may be sometimes questionable; some of them may contain bugs which need to be eventually eradicated by the developers (Metruk, 2020). It should also be noted that EFL instructors should aid in hel** their learners select proper apps.

5 Discussion and conclusion

This article attempted to explore, summarize, and characterize the use of portable devices for the purposes of pronunciation acquisition and practice. Out of the initially identified 300 articles, only 15 remained as they were considered eligible for the purposes of this systematic literature review, which is based on PRISMA 2020.

It was established that according to the reviewed articles, mobile learning (mobile-assisted language learning) demonstrates a beneficial influence on L2 pronunciation acquisition. The findings are in line with, for example, those of conducted by Arashnia and Shahrokhi (2016), **g (2017), Kaiser (2018), and Walesiak (2017). However, throughout the course of its investigation, several researchers have questioned the effectiveness of pedagogical interventions within courses, raising a number of questions. For example, it is debatable whether there is a sufficient amount of pedagogical aspects, or how much priority ought to be assigned to technology within the teaching and learning process. Furthermore, numerous apps are not designed for explicit pronunciation practice, and there is also the issue of providing adequate feedback when using m-learning for pronunciation purposes. This area of foreign language instruction appears to be underexplored, and further empirical studies involving statistical support as well as discussing pedagogical elements of MALL need to be carried out.

The second research question concentrated on the attitudes of learners toward m-learning in the reviewed articles. It is confirmed that m-learning has achieved popularity among EFL learners and that it has its place in future teaching and learning as the majority of learners within the studies demonstrated positive attitudes toward mobile learning. These outcomes are in line with those of Botero et al., 2018, Saidouni and Bahloul (2016), and Tra (2020). The finding appears to be linked with the fact that younger generations consider their smart device (smartphones in particular) to be a rather vital part of their lives that can also be utilized for language learning purposes, exploiting the device in an innovative and exciting way for learning L2. Nonetheless, there are questions that need to be raised. For instance, it is the matter of learners’ (and teachers’) preparedness for using smartphones in EFL instruction. Furthermore, there are questions concerning their distraction from the learning process or employing smart devices for the purposes of speculative and unacademic behavior. Future studies should also concentrate on opinions and attitudes toward mobile learning in relation to EFL instruction.

The third research question focused on the types of mobile devices and apps/platforms involved. It seems that smartphones are the most prevalent mobile device identified in the studies. However, tablets or iPads were also mentioned. Smartphones stand in the center of attention, playing a major role in the lives of learners. As far as pronunciation apps are concerned, a variety of apps were employed (Table 3), but as has already been mentioned, there exist numerous challenges one must address due to the fact that new apps are developed all the time. For instance, it appears to be difficult for language learners to choose a suitable app since there is a massive amount of applications readily available on the market. Another aspect is concerned with its functionality – apps might not work in a way they were designed and may contain bugs, which makes it difficult to facilitate the process. It is also the appropriateness that seems to be in doubt as it can be a rather difficult task to find and employ apps that are perfectly appropriate for develo** particular language systems (e.g., the phonological one and its partial components) or skills. One of the solutions to these challenges might lie in increased mutual cooperation between students and their instructors, who need to possess a range of skills in this area of expertise. The skills can be acquired by completing relevant university degree in the given field, undergoing subjects and courses that concentrate on this matter so that their level of preparedness for adequate implementation of mobile devices and apps is markedly increased. However, it may be the lifelong education of individual teachers in the given field which can make the most significant difference as mobile apps are developed round the clock. Indubitably, much remains to be explored in the realms of employing mobile learning for the purposes of pronunciation acquisition.

Other issues, such as physical properties (e.g., smaller screen size, issues with batteries), connectivity issues, price, multitasking problems, and the like clearly merit attention of educators and researchers. Further, learners tend to be distracted by using their smart devices at their lessons, employing them to a high extent for nonacademic purposes (social networking, chatting with peers, etc.). Alternatively, it is also the possibility of isolation and lack of social contact which may come into being. The examples that have been mentioned demonstrate that there exist a number of considerable challenges which need to be confronted and eventually overcome by language teachers. A potential solution here may be that teachers agree on certain rules of implementing mobile devices into the teaching and learning process, holding regular discussion meetings on this matter with their peers. This will certainly increase their workload, but it appears to be the necessary step towards the more effective and higher-quality use of mobile devises for the purposes of language learning. Other options include the use of artificial intelligence and augmented reality; yet again, despite the fact that it is the learner-centered approach that is being advocated, teachers are required to take the first step so that this type of new technology is adequately mirrored in the teaching and learning process, generating pedagogically sensible environment.

Future studies should, therefore, focus on empirical evidence – seeking statistically sound articles that discuss the effectiveness of mobile learning. Further, addressing the issue of attitudes and motivation regarding MALL for pronunciation purposes also appears to be underexplored. It is still the case that other language systems (e.g., vocabulary, grammar) or skills (e.g., reading or listening) are explored to a higher degree. However, pronunciation acquisition and instruction need to be devoted adequate attention, as it is often this aspect of language that causes intelligibility problems and breakdowns in communication.