Abstract: A sound suppression apparatus for installation inside a gas transport duct is provided. The sound suppression apparatus comprises a resistive sound-absorbing element (110) and a housing providing a reactive sound-attenuating element (130) communicating with a surrounding of the apparatus via opening in an outer surface of the housing. An outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing. A gas transport duct comprising the sound suppression apparatus is also provided.

Abstract: A sound suppression apparatus for installation inside a gas transport duct is provided. The sound suppression apparatus comprises a resistive sound-absorbing element (110) and a housing providing a reactive sound-attenuating element (130) communicating with a surrounding of the apparatus via opening in an outer surface of the housing. An outer surface of the sound suppression apparatus comprises an outer surface of the resistive sound-absorbing element and the outer surface of the housing. A gas transport duct comprising the sound suppression apparatus is also provided.

Abstract: In the present invention a controllable acoustic source (14) in connection with the process fluid (10) emits a signal (18) into the fluid (10), consisting of a suspension of particles (12), being volumes of gas, liquid or solid phase. The controllable acoustic signal (18) is allowed to interact, with the particles (12), and the acoustic (pressure) signals (22) resulting from such an interaction is measured preferably via a sensor (24). A spectrum is measured. The spectrum is used to predict properties, content and/or size of the particles (12) and/or used to control a process in which the process fluid (10) participates. The prediction is performed in the view of the control of the acoustic source (14). The used acoustic signal has preferably a frequency below 20 kHz.

Abstract: A sound reduction system for reducing noise from a high power combustion engine is supplied by means of a method. The sound reduction system comprises a plurality of elements and attenuating devices placed in an elongated channel. During design of the sound reduction system one makes use of a particular suitable attenuating element with a first reactive part, a second reactive part and a third reactive part. Such a module, which is less sensitive to position in the channel, cost effective to manufacture and cost effective to model, is combined with single attenuating devices. The method enables a user to meet the requirements on sound reduction and keeping construction costs down, by using an iterative step-by-step approach. Such an approach is unknown according to traditional methods. An advantage of the method is that it enables an accurate acoustic model of the complete exhaust system, not only in the low frequency area and in the upper frequency area, but also in the intermediate frequency area.

Abstract: A light absorbent for hygienic spaces comprising a porous mat. The normalized flow resistance of the mat is in the interval of 0.5-2.

Abstract: In the prevent invention a controllable acoustic source (14) in connection with the process fluid (10) emits a signal (18) into the fluid (10), consisting of a suspension of particles (12), being volumes of gas, liquid or solid phase. The controllable acoustic signal (18) is allowed to interact with the particles (12), and the acoustic (pressure) signals (22) resulting from such an interaction is measured preferably via a sensor (24). A spectrum is measured. The spectrum is used to predict properties, content and/or size of the particles (12) and/or used to control a process in which the process fluid (10) participates. The prediction is performed in the view of the control of the acoustic source (14). The used acoustic signal has preferably a frequency below 20 kHz.