Abstract: An acoustic transducer is disclosed for incorporation into an engine exhaust system or other gas carrying duct. The transducer produces pressure variations within the duct in accordance with an applied electrical signal. The transducer is especially suitable for use as part of a noise cancellation system whereby inverse pressure variations produced by the transducer cancel noise propagating in the duct. The design of the transducer allows its use when the duct is one carrying high temperature gases such as an automobile exhaust pipe.

Abstract: An acoustic diaphragm is made of metallic sheet material forming a raised pattern of the material and unraised sectors of the material. The diaphragm is of the dome-shaped variety. The raised pattern incorporates sets of raised strip elements. There is a set of such elements extending radially from the vicinity of the apex. There is a set extending along areas of the sheet material between the radially extending elements, this second set including pairs of strip elements which intersect one another along such areas. There is also a set of circumferentially extending raised strip elements. The form of the radially extending elements changes along their lengths; for example, they rise to levels which vary along their lengths.