  This work addresses the response functions for infinite beams and plates with
a force excitation at the origin of the coordinate system and its application
to time reversal and time frequency analysis. The response function for
Euler-Bernoulli beams is derived and for plates revisited. Interpretation
concerning energy conservation and mobility are given. An possible alternative
method to measure the coupling loss factors in SEA is sketched. \\
  The impulse response of a finite beam is measured in an experiment and
compared with that predicted theoretically. The experimental data before the
first reflection of the pulse showed good agreement with the theory. The
response function is used to simulate a time reversed pulse. This numerical
simulation is verified with an experiment.
