  The naive calculation of black hole evaporation makes the thermal emission
depend on the arbitrary high frequency behaviour of the theory where the theory
is certainly wrong. Using the sonic analog to black holes-- dumb holes-- I show
numerically that a change in the dispersion relation at high frequencies does
not seem to alter the evaporation process, lending weight to the reality of the
black hole evaporation process. I also suggest a reason for the insensitivity
of the process to high frequency regime.
