Complex sentence: Liners are applied on the internal walls of the engine nacelle, both in the intake and by-pass ducts, and use Helmholtz resonance for the dissipation of incident acoustic energy.
Split into simpler sentences: Liners are applied on the internal walls of the engine nacelle, both in the intake and by-pass ducts. These acoustic liners use Helmholtz resonance for the dissipation of incident acoustic energy.