A resonance detection device is provided for detecting resonance in an exhaust passage of an automotive vehicle. The detection device employs a temperature sensor in combination with an arrangement which enables the sensor to be exposed to a flow of exhaust gas the temperature of which is different from the temperature of the bulk of the flow, when resonance occurs. In given embodiments the arrangement takes the form different diameter conduits and/or vessels, while others it takes the form of a heat exchange device which either heats or cools the gases, and which is disposed proximate the temperature sensor. When no resonance occurs in the passage, the output of the temperature sensor remains stable. When resonance occurs the fluid flow characteristics in the passage change in a manner wherein the gas which has been either heated or cooled by the heat exchange device is induced to flow against the temperature sensor. The sensed temperature change can be used to control a valve via which the resonance characteristics of the passage are modified and via which resonance is attenuated.