  We investigate the spectrum of stochastic gravitational wave background
generated by hybrid topological defects: domain walls bounded by strings and
monopoles connected by strings. Such defects typically decay early in the
history of the universe, and their mass scale is not subject to the constraints
imposed by microwave background and millisecond pulsar observations.
Nonetheless, the intensity of the gravitational wave background from hybrid
defects can be quite high at frequencies above $10^{-8} Hz$, and in particular
in the frequency range of LIGO, VIRGO and LISA detectors.
