This book presents sixteen chapters in Volume 1. This Volume I of the Proceedings of the Worldwide Music Conference 2021 offers a smorgasbord of scientific approaches to music. The congress is one of a kind; it is dedicated not to a specific field but to the interdisciplinary developments and the interaction with the representatives from actual scientific disciplines. The languages of mathematics, computer science, semiotics, palaeography, and medicine are in the mix; geography of the studies is also impressive-Greece, Mexico, China, Russia, India, Poland, and USA, to name just a few. The purpose of such juxtaposition is to see how the terminology, categorical apparatus, and interpretations of music vary from science to science and how this can enrich the terminology of music theory. They cover a wide range of topics that the editors divided into four subfields: music in interdisciplinary contexts, music and current technology, musical instruments and voice, and music pedagogy and medicine. The opening section of the Proceedings is thus dedicated to the idea of interdisciplinarity, relationship of creator of theory of harmony Rameau to sciences of his time, the idea of number in music, co-creation, and the category of musical network. Three more chapters here deal with Russian palaeography, Indian musical genre, and the idea of musical semiotics. It is a kind of opening statement from music theorists. Part two, music and current technology, united three chapters, on "zero gravity" concept in modern music, discussion of scales as mathematical networks, and the innovation in digital music making, transforming it from stationary to mobile applications. The third part, musical instruments and voice, is of special interest because it is in the study of the instruments, the design, acoustic characteristics, and tuning, and sciences have cooperated with music theory for centuries. In addition to instruments, one chapter here is dedicated to voice. The last part, musical pedagogy and medicine, takes the reader even further into the interdisciplinary domain. The Proceedings is written in standard English language, prepared for the pleasure of reading of wide circles of professionals in different fields. The purpose of the editors is to bring this rather diverse set of texts into the context of a fruitful dialogue.