Exceptional points (EPs), as unique spectral singularities in non-Hermitian systems, play a crucial role throughout the study of non-Hermitian physics. Despite extensive investigations on single or isolated EPs, the collective behavior of multiple EPs and their intricate interplay remain largely unexplored, particularly in experiments. Here, we demonstrate a universal non-Abelian conservation rule that governs the collective interactions of multiple EPs. Specifically, we construct a two-dimensional three-band non-Hermitian lattice and experimentally implement it using an acoustic coupled-resonator system in synthetic momentum space. By measuring eigenfrequency braids, we precisely identify the topological charges of EPs and observe distinct braiding consequences for momentum loops enclosing the same EP. More intriguingly, by tracking the transmutations of multi-EP charges, we evidence that two pairwise-created EPs do not annihilate upon collision but instead coalesce into a new higher-order EP. Our findings represent a major advance in exploring non-Hermitian non-Abelian physics, potentially unlocking new avenues for applications.

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• Acoustic metamaterials
• Exceptional points
• Non-Hermitian systems
• Non-Abelian models