  Acoustic analogues of black holes (dumb holes) are generated when a
supersonic fluid flow entrains sound waves and forms a trapped region from
which sound cannot escape. The surface of no return, the acoustic horizon, is
qualitatively very similar to the event horizon of a general relativity black
hole. In particular Hawking radiation (a thermal bath of phonons with
temperature proportional to the ``surface gravity'') is expected to occur. In
this note we consider quasi-one-dimensional supersonic flow of a Bose--Einstein
condensate (BEC) in a Laval nozzle (converging-diverging nozzle), with a view
to finding which experimental settings could magnify this effect and provide an
observable signal. We identify an experimentally plausible configuration with a
Hawking temperature of order 70 n K; to be contrasted with a condensation
temperature of the order of 90 n K.
