With the growth of education in multilingual setting, language teachers who teach in multilingual settings are now facing challenges in adapting new linguistic environments where multiple language contacts take place. It is therefore necessary to educate pre-service and in-service teachers on how multilingualism influence language learning, and one of the key areas is L2 pronunciation teaching, in which teachers could conduct their own mini-research, or even guide their students to conduct ones, to facilitate their understanding and acquisition. Traditional phonetic research relies mainly on sound collection which requires labour forces and equipment. Conventionally, to obtain sound samples from/under a controlled environment, good quality microphones are essentials for both on-site and off-site data collection (Munro and Derwing, Pronunciation in Second Language Learning and Teaching Proceedings, 11(1), 2020) and the assistance from other research team members is needed for off-site collection. However, with the development of the Internet, there have been multiple studies using online sources for phonetic research (e.g. Sewell and Chan, English World-Wide, 31(2):138–161, 2010; Chan and Chan, Journal of Universal Language, 22(2):1–44, 2021). Internet-based corpora are usually composed of sound clips recorded under uncontrolled environments with varied recording quality. Studies using Internet-based corpora have demonstrated the advantage of having an easier data collection process, especially under the pandemic era when on-site data collection is sometimes not possible. Internet-based corpora are also effective in long-distance data collection for individual researchers with limited help. It is surely one interesting way for (pre-service and/or in-service) teachers to conduct their own research in order to deepen their understanding in multilingualism. Despite the obvious advantages, researchers may still question the validity and quality of such data source in phonetic studies. Therefore, this chapter aims to suggest an interesting plan for teacher educators, in which (pre-service and/or in-service) teachers could conduct their own research in L2 phonetics and phonology by creating their own corpora with online sources or using existing well-established spoken corpora such as the Asian Corpus of English (ACE. The Asian corpus of English. Director: Andy Kirkpatrick; Researchers: Wang Lixun, John Patkin, Sophiann Subhan. https://corpus.eduhk.hk/ace/index.html , 2020). In that way, teachers could have a better understanding in how multilingualism may affect L2 pronunciation. This chapter will also investigate the challenges over these phonetic studies which utilised internet sources. In addition, recommendations on how to use these Internet-based corpora for future research opportunities will be discussed. This chapter aims to provide insights for researchers by examining the risks and potentials of Internet-based corpora, and suggesting some ideas of how to use such corpora for future language teacher education.