Abstract: The invention provides a silencer for high velocity gas flow which includes a flow passage 2 and a domed, perforated plate 1 which terminates the flow passage, wherein the perforated portions 9 of the plate are distributed over the plate so as to direct gas from the passage as plurality of divergent jets 7 whereby noise is produced with a frequency at maximum intensity in a range of the audible spectrum at which human auditory perception is relatively insensitive. Such a silencer may be used to reduce the perceived noise emitted by a gas turbine engine when for reasons of engine handling and response excess air bled from the compressor stages.