<p dir="ltr">The energy sector is facing significant challenges from global sustainability targets and increasing energy demand. Combustion plays a crucial role by providing the majority of the global energy supply. Therefore, to achieve these goals, combustion systems must become more efficient and cleaner. Although hydrogen offers a carbon-free alternative to conventional fuels, it also poses major challenges, such as thermoacoustic instabilities when burned in gas turbines, which are widely used in power generation and aviation. The aim of my thesis is to gain a fundamental understanding of how acoustics change when switching from methane to hydrogen, using high-fidelity simulations and experiments. The goal is to make gas turbines safer, more efficient and reliable. This research will facilitate the transition towards decarbonisation in future energy systems.</p>