  Damping typically results in attenuation of vibrations and elastic wave
propagation in mechanical systems. Contrary to this conventional understanding,
we demonstrate experimentally and explain theoretically the revival of an
elastic wave transmitted through a periodic metastructure when a weak
non-Hermitian defect (damping mechanism) induces violation of time-reversal
symmetry. Damping alters the nature of the system's resonant modes, instigating
interference in the scattering field. This leads to transmission revival,
revealing the presence of hidden modes which are otherwise masked by the
symmetry. Our findings offer an innovative approach for designing
dissipation-driven switches and controllers and non-destructive structural
health monitoring systems.
