  This paper presents an application of time-frequency methods to characterize
the dispersion of acoustic waves travelling in a one-dimensional periodic or
disordered lattice made up of Helmholtz resonators connected to a cylindrical
tube. These methods allow (1) to evaluate the velocity of the wave energy when
the input signal is an acoustic pulse ; (2) to display the evolution of the
spectral content of the transient signal ; (3) to show the role of the
localized nonlinearities on the propagation .i.e the emergence of higher
harmonics. The main result of this paper is that the time-frequency methods
point out how the nonlinearities break the localization of the waves and/or the
filter effects of the lattice.
