Seyhun Topbas¿ is professor of Speech & Language Pathology at Anadolu University, Turkey. She is one of the pioneers of Speech and Language Pathology profession in Turkey; the founder of the graduate programs in Speech and Language Therapy and DILKOM (Education, Research and Training Centre for Speech and Language Pathology) at Anadolu University. Dr. Topbas has developed the first standardized Turkish Articulation and Phonology Test and published on phonological disorders in a variety of books and journals. She is currently on the editorial board of Clinical Linguistics and Phonetics.

Mehmet Yavaſ is professor of Linguistics at Florida International University, Miami, Florida. His main area is phonology and its application to language acquisition and to speech and language disorders. His articles on Applied Phonology have appeared in numerous journals. He is the principal author of Avaliaçao Fonologica da Criança (a phonological assessment procedure for Brazilian Portuguese). His other publications are Phonological Disorders in Children (Routledge, 1991), First and Second Language Phonology (Singular, 1994), Phonology: Development and Disorders (Singular 1998), Applied English Phonology (Blackwell, 2006).