  We have examined gravitational wave echo signals for nine binary black hole
merger events observed by Advanced LIGO and Virgo during the first and second
observation runs. To construct an echo template, we consider Kerr spacetime,
where the event horizon is replaced by a reflective membrane. We use
frequency-dependent reflection rate at the angular potential barrier, which is
fitted to the numerical data obtained by solving Teukolsky equations. This
reflection rate gives a frequency-dependent transmission rate that is
suppressed at lower frequencies in the template. We also take into account the
overall phase shift of the waveform as a parameter, which arises when the wave
is reflected at the membrane and potential barrier. Using this template based
on black hole perturbation, we find no significant echo signals in the binary
black hole merger events.
