About the Author: Antoinette am Zehnhoff-Dinnesen studied medical sciences in Düsseldorf and Bonn. In 1983 she became a medical specialist in ENT diseases and in 1986, a medical specialist in phoniatrics and paedaudiology. In 1988, she gained her Habilitation from Düsseldorf University for her work on regulation of vocal amplitude and frequency during voice onset. In 1990 Dr. am Zehnhoff-Dinnesen was appointed Professor of Phoniatrics and Paedaudiology at the Medical Faculty of Philipps University in Marburg. The following year she became Professor at the Medical Faculty at the Westphalian Wilhelms University of Münster, where she was Head of the Clinic of Phoniatrics and Paedaudiology until her retirement in 2020. She is author or co-author of more than 150 original papers in German and English on various aspects of phoniatrics and paedaudiology, and co-author of several books. She has been both Secretary and President of the German Society of Phoniatrics and Paedaudiology, President of the Union of the European Phoniatricians (UEP) and has initiated and promoted the foundation of the European Academy of Phoniatrics as the founding director. She and her team have received several awards. Antoinette am Zehnhoff-Dinnesen is honorary chairwoman of the Union of the European Phoniatricians and honorary member of the Polish Society of Otorhinolaryngologists and Head and Neck Surgeons, of the Czech Society of Otorhinolaryngology and Head and Neck Surgery, of the German Society of Phoniatrics and Paedaudiology, of the European Academy of Phoniatrics and of the Confederation of German Hearing Screening Centres.
Joseph Sopko, Prof.Dr.med Dr.h.c., began his study of medicine in his native town of Kosice, Slovakia. Later he continued his studies at the University of Basel, Switzerland, where he habilitated with a speciality in phoniatrics, and in 1991 was elected full professor (Extraordinarius) for otorhinolaryngology and phoniatrics. In 1975 Professor Sopko founded the Phoniatrics and Paediatric Audiology Department in the ORL University Clinic, Basel and worked there as head until 2003. He led the speech therapy school at the University Basel from 1975 to 2002. 1995 he also founded the Phoniatric department in the ORL - Clinic, Kantonsspital Aarau and worked there for more than 20 years. He is the phoniatrician to the Basel Opera and Stadttheater, and also has a private practice in Basel. In 2002 he received an Honorary Doctorate from the University of Kosice. His scientific-publishing activity includes more than 80 articles and book contributions.

Marie-Claude Monfrais-Pfauwadel, Dr, studied medicine at the René-Descartes University in Paris and then trained in ENT and Phoniatrics, graduating in 1978. She completed her education with degrees in Psychology and Psychoanalysis at Paris-6 University (MBS) and Linguistics and Phonetics at Paris-3 and Paris-6 Universities (MBS). She gained her degree in Phonetics by working on the nosology of disfluencies and their physiopathology. Later she added a speciality degree in Muscle physiology and Myopathies at the Pitié-Salpetrière Hospital in Paris. She worked for more than 10 years in the Voice/Speech/Language Clinic at the Pitié-Salpetrière Hospital in Paris, then created the Voice and Speech Laboratory in the new Georges Pompidou Hospital in 2000, alongside a "Stuttering Clinic". Meanwhile she obtained in 1985 the first scholarship from the Stuttering Foundation of America at Northwestern University to become acquainted with the latest techniques and research discoveries about speech motor control and stuttering. Back in France she started teaching the clinical, physiological, linguistic and phonetic aspects of stuttering, and created a two-year MS degree devoted to Stuttering for Phoniatricians and Speech Therapists in 2005, which is still running. She has authored and co-authored several books on Voice disorders, Stuttering clinics, Stuttering therapy and neurolinguistics and many journal articles. She was twice elected President of the French Medical Phoniatric Society. She was one of the founding members of the International Fluency Association (IFA) in 1993 and was a member of the IALP Fluency Committee for twenty years since its founding. She retired from practice in 2012, but kept teaching Clinics and Phonetics for Phoniatricians and Speech Pathologists. Recently she was asked to join the ANR Programme in Montpellier-3 University about the role of the "Frontal Aslant tract" in the genesis of stuttering. She is actually co-responsible of this programme which will run for the next three years.

Katrin Neumann studied medicine at the University of Leipzig. She is Professor of Population Medicine of Communication Disorders at the University of Münster and Director of the Department of Phoniatrics and Paedaudiology at the University Hospital Münster, Germany. She is editor-in-chief of the Journal of Fluency Disorders (Elsevier) and co-editor of the journals Communication Disorder Quarterly and LOGOS. As a WHO expert advisor, she contributes to the work of the WHO Programme of Prevention of Deafness and Hearing Loss and of the WHO Rehabilitation Programme. She is WHO representative of the Union of European Phoniatricians (UEP), the German Society of Phoniatrics and Paedaudiology (DGPP) and the German Society of Audiology (DGA). She has published more than 270 original articles, monographs, guidelines and book chapters and has received a number of national and international awards. Her research interests include neuroimaging and population medicine of hearing, speech fluency, developmental language and voice physiology and pathology.