The central theme of this collection is the epistemological status of constraints and preferences in linguistics. The contributions focus mainly on phonology; one article deals explicitly with morphology. The approaches to phonology represented in the volume are those of Natural Phonology, Government Phonology, Optimality Theory, autosegemental phonology, and computational phonology. Constraints are juxtaposed either to rules or to preferences in the discussion of constraint-based vs. preference-based theories.

The choice of a pronunciation model for the 21st century learner has become a major issue of debate among applied linguists concerned with teaching English. The standard pronunciation models - Received Pronunciation and General American - have recently been confronted with a new proposal of a Lingua Franca Core (LFC) or English as a Lingua Franca (ELF), put forward as a didactic priority in teaching English pronunciation to foreigners. This volume, which includes selected contributions from the Poznań Linguistic Meetings of 2003 and 2004, does not intend to present yet another model, but sets out to place the teaching and learning of English pronunciation in the context of the 21st century. As the needs of English users are clearly changing fast in the globalizing world, the question is to what extent, if at all, models of pronunciation have been able to keep up with them, and whether they in fact should do so. Thus, key issues in the integration of pronunciation into English as L2 curricula are explored.

This publication constitutes a selection of papers presented at the 6th International Symposium on the Acquisition of Second Language Speech, New Sounds 2010, held in Poznan, Poland. It consists of two volumes, presenting state-of-the-art achievements and perspectives for future research related to the acquisition of second language phonetics and phonology. The key issues include the development of explanatory frameworks of phonological SLA, the expanded scope of domains under investigation, modern methods applied in phonological research, and a new take on the causal variables related to ultimate proficiency in L2 speech. This first volume contains a selection of 27 articles that cover a wide variety of themes including L2 speech perception and production, segmental and prosodic features, as well as factors related to foreign accentedness, individual variability and ultimate achievement in the acquisition of speech.