  In this work, we analytically report Coherent Perfect Absorption induced by
the acoustic nonlinear response of a Helmholtz Resonator side loaded to a
waveguide. In particular, we show that this two-port acoustic system can
perfectly absorb two high amplitude symmetric incident waves when the additive
nonlinear losses in the HR, induced by the jet flow separation, together with
the weak linear viscothermal losses of the HR balance the radiation losses to
the waveguide. For the case of the one-sided incidence configuration, this
condition leads to an absorption equal to 0.5. This result, which is verified
experimentally, is in a good agreement with an analytical nonlinear model of
the impedance of the HR. The nonlinear control of perfect absorption using
resonators will open new possibilities in the design of high amplitude sound
attenuators for aero-engine applications.
