Engine order cancellation (EOC) systems generate feed forward noise signals based on the engine or other rotating shaft RPM and use those signals and adaptively configured W-filters to reduce the in-cabin SPL by radiating anti-noise through speakers. An EOC system may include a signal analysis controller for detecting non-stationary events, such as speech, based on parameters sampled from a current frame of error signals output from microphones positioned in various locations of a vehicle passenger cabin. Upon detection, the signal analysis controller may mitigate the effects of the non-stationary event to prevent the EOC system from boosting noise or contributing to a speech-like post-echo in the passenger cabin. For example, if speech is detected in a frame, then the adaptation can be frozen for that frame. Alternatively, the signal analysis controller may adaptively subtract voice signals out of the error microphone signal.

A sound signal control device in a device including an input transducer to detect sound in a space in a vehicle, a sensor to image an occupant in the space, and an output transducer to emit sound into the space includes: a controller to generate information indicating a position of a head of the occupant and information indicating a state of the occupant, based on an image imaged by the sensor; a processor to generate a cancellation signal for cancelling noise at the position based on a sound signal representing sound detected by the input transducer and the information, and generate a control signal for controlling sound at the position based on the cancellation signal; and a converter to cause the output transducer to emit a sound corresponding to the control signal. The processor adjusts a degree to which the noise is cancelled, based on the information indicating the state.

A active noise cancellation (ANC) system may include an adaptive filter divergence detector for detecting divergence of the one or more controllable filters as they adapt, based on various temporal or frequency domain amplitude characteristics. Upon detection of a controllable filter divergence, the ANC system may be deactivated, or certain speakers may be muted. Alternatively, the ANC system may modify the diverged controllable filters to restore proper operation of the noise cancelling system. This may include adjusting a leakage value of an adaptive filter controller.

A loudspeaker arrangement includes an air-tight, rigid, thermo-conductive enclosure (103) with an aperture (115) and an outer surface, and a loudspeaker (101) air-tightly mounted in the aperture (115) to form a locked acoustic volume within the enclosure (103). The arrangement further includes a multiplicity of thermo-conductive fins (112) attached to or integrated in the enclosure (103) at the outer surface thereof. The multiplicity of fins (112) is distributed over the outer surface of the enclosure (103).

A vehicle exhaust component includes a body with an open inner cavity providing a fixed volume and a neck having one end associated with the fixed volume and an opposite end associated with an exhaust gas flow path. A flexible membrane separates the fixed volume into a first chamber and a second chamber. An actuator is used to vary a tension of the flexible membrane.

A vehicle outside microphone unit detects noises outside a vehicle and has a sound channel that has an entry opening terminating at a microphone. In an orientation in which the microphone constitutes an uppermost point of the sound channel, a sound channel makes a bend upwards, starting from the entry opening, and is generally configured as a water drain. Further, a vehicle acoustical system having such a vehicle outside microphone unit and a vehicle having a corresponding vehicle acoustical system are described.

A high pressure melamine plant comprising a synthesis section and a melamine purification section, wherein the synthesis section provides a first melamine-containing stream (6), and said melamine purification section comprises: a quencher (2) receiving said first melamine-containing stream (6) from the synthesis section; a stripper (3) fed with a second melamine-containing stream (7) from said quencher (2), wherein purified melamine (11) is collected and vapours (10) are extracted; a heat exchanger (12), wherein said vapours (10) are condensed providing a condensed stream (14); an absorber (4) fed with said condensed stream (14) providing an aqueous solution (15) comprising ammonia and carbon dioxide, at least a portion (15b) of said aqueous solution being exported from the purification section (200) of the plant.

A sound generating system for an exhaust system of an internal combustion engine of a motor vehicle includes an electrically actuatable sound generating device to generate sound outside a vehicle interior space. A sound sensor is configured to detect the sound generated by the sound generating device in combination with sound carried by an exhaust gas stream outside the exhaust system. The sound sensor is arranged in a region of a license plate or a rearview camera of the motor vehicle. Furthermore, a motor vehicle includes such a sound generating system. In addition, there is presented a sound sensor unit for such a sound generating system.

An exhaust gas system for an internal combustion engine of a motor vehicle includes at least one exhaust gas line and an active sound-generation device, which comprises a sound line with a mouth that opens into the exhaust gas line and is connected to an electrical sound source. A housing surrounds at least one portion of the exhaust gas line arranged downstream of the mouth of the sound line into the exhaust gas line when viewed in a flow direction of the exhaust gas. The said housing is connected to an error sensor and a cavity is formed between an outer side of the exhaust gas line and an inner side of the housing. The at least one portion of the exhaust gas line extending in the housing has at least one opening that opens into the cavity.

An active noise cancellation system and method, in which an active noise controller generates an anti-noise signal based on an error signal, and a loudspeaker operatively coupled to the active noise controller converts the anti-noise signal into anti-noise sound. An acoustic error sensor operatively coupled to the active noise controller picks up sound and converts the picked-up sound into the error signal. The acoustic error sensor is disposed at a front face of the loudspeaker.