Last year Joël Gilbert passed away. This communication aims at introduce the special session devoted to him during FA2023 by taking a synthetic view of his contributions concerning the acoustics of wind instruments. Being an excellent trombonist, he was very interested in the acoustic functioning of brass instruments. In his PhD in 1991, he studied the relationship between resonance frequencies and playing frequencies. For this purpose, he built many experiments, based upon small modifications of the geometry of a saxophone. Extending methods of nonlinear electronics, he showed that the Harmonic Balance can be used for auto-oscillations, the playing frequency being an unknown. His publications dealt with many subjects, even non-musical, such as animals or internal combustion engines. Of major interest are all papers concerning the development of shock waves in - a trombone, then a comparison criterion for the different types of brass instruments, called brassiness. This result was an original way for studying the wide variety of brass instruments. This was an important part of the book ”The Science of Brass Instruments”, an outstanding source of information for both scientists and musicians, recently published with Murray Campbell and Arnold Myers.