1 Introduction

This article introduces five language change research series published by Routledge since 2019, which provide quantitative research methods guidance on the social basis of language change through empirical investigation and case studies. The book 'Urban Contact with Dialects and Language Changes: A Global North South Perspective', published in March 2022, systematically compares urban contact with dialects in the North and South of the world, and explores the emergence and development of dialects in major cities in sub Saharan Africa and northwestern Europe. The book focuses on contemporary urban environments, analyzing the new language practices and mixed speech styles formed in the context of large-scale immigration, as well as the contact between new dialects and existing languages or dialects. By comparing the language variation and change patterns between African and European cities, the commonalities of language phenomena and language differences between multilingual and monolingual societies were examined.

Academic background and related research review of the two editors in chief

Paul Coswell and Heike Weiss are the editors in chief of "Urban Contact with Dialects and Language Change: A Global North South Perspective," and they explore language variation and change in urban environments in the introduction and independent chapters. Koswell is a British sociolinguist known for his research on the language of rural immigrants in Bergen, Norway. He proposed the dialect contact model and the "nest dwelling" language community theory. He has led multiple large-scale projects and made significant contributions to the development of dialect contact theory. In the book, he discusses the emergence of multicultural London English (MLE) among young people in working-class communities in the inner city of London, revealing its phonological, morphological, syntactic, and discourse features through empirical corpus, as well as sociolinguistic findings related to language variants, style, dialect and acquisition, race, and identity. MLE speakers come from different ethnic and cultural backgrounds and have become a well-known variant of English social dialects.

The emergence and development of dialects in major cities in sub Saharan Africa and northwestern Europe

The book "Urban Contact with Dialects and Language Changes: A Global North South Perspective" explores in depth the phenomenon of language contact and change in different cities around the world through two parts, A and B. Part A focuses on sub Saharan African cities in a multilingual social context, such as the English French mixed variant of Kafurane in Cameroon, the Lingala variant in Kinshasa, Congo, Wolof in Senegal, Tar and urban vernacular forms in South Africa, Pichin English in Ghana, Sheng and English in Kenya, and Helsinki slang in Finland. These studies reveal the development of youth language, urban language, and contact language, as well as how they interact with urban identity and multilingual societies.

Theoretical origins and development of language research among urban youth

Explored the theoretical origins and development of research on language changes among urban youth. The research case focuses on the urban youth population, with age as a key social factor in language variation. Early research was mainly based on LaBeouf's paradigm of linguistic community variation, without involving language contact. Labov emphasized the importance of the social environment, especially the age of the speaker. Trugir proposed the impact of social and linguistic environments on language change, but lacks empirical support. Milton Keynes' study found that children and adolescents are the main sources of phonetic changes by comparing their language with that of their parents. Koswell proposed a three-stage model of language change in children and adolescents, focusing on the guidance of interpersonal relationships on change at different stages. This study has a direct impact on the research of adolescent English, and Milton Keynes' research is the first to explore in detail the issue of language variation in the process of urbanization, which has an important impact on promoting the development of sociolinguistic research.

5 Conclusion

The book emphasizes the diversity of research methods and the depth of empirical investigations, revealing the impact of urban dialect exposure on language change and providing new perspectives for multiple linguistic fields. The case study in southwestern Germany provides new insights into age and language change, emphasizing the importance of global sociolinguists delving into language communities for case studies and suggesting that this may be an effective way for Chinese scholars to contribute to global sociolinguistic research.