This paper explores the transfer of knowledge across geographical and disciplinary boundaries in the development of Czech phonetics during the 20th century. It focuses on how international academic mobility – including study stays abroad and internships in Prague – contributed to the formation of a dense network of intellectual exchange. These personal connections were reinforced through correspondence, the exchange of books and offprints, and participation in international congresses, which functioned as critical hubs for the circulation of phonetic knowledge. Equally important was the interdisciplinary nature of early phonetic research, which drew from linguistics, acoustical physics, medicine or scientific cinematography. In turn, phonetics enriched adjacent domains such as speech therapy, language teaching, and dialectology. By examining the case of Czech phonetics, this study highlights the broader significance of such crossings in shaping the evolution of the phonetic sciences.