Paul Clavin is Professor Emeritus at Aix-Marseille Université and an honorary member of the Institut Universitaire de France, where he was Chair of Mécanique Physique from 1993 to 2004. In 1995, he founded the renowned research institute, the Institut de Recherche sur les Phénomènes Hors Équilibre (IRPHE). He has received major awards from the Société Française de Physique (Plumey, 1988), the French Academy of Sciences (Grand Prix, 1995) and the Combustion Institute (Zeldovich Gold Medal, San Francisco, 2014). Geoff Searby is retired Director of Research at the Institut de Recherche sur les Phénomènes Hors Équilibre (IRPHE). He is a renowned specialist of the physics of thermo-acoustic instabilities in combustion chambers and rocket motors, and his experiments have made major contributions to the understanding of the dynamics of flame fronts. In 2004, he obtained a major award from the French Academy of Sciences.