Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Gebhardt Ventilatoren Gmbh & Co.

Helmut V Fuchs

Xueqin Zha

Philip Leistner

Gerhard Babuke

Dietmar Eckoldt

Jan Krueger

Roland Lippold

Ulrich Ackermann

Joachim Mohr

Andreas Jacobs

Xuegin Zha

Joerg Hunecke

Norbert Rambausek

Heinz Weiland

Carl-Alexander Voigtsberger

Moritz Spaeh

Gerold Schupp

Structured pre-form bodies as panel lining for wide-band sound absorption are made of an open-cell foam material having a rigid framework co-vibrating in a resonant manner at low frequencies. The pre-form bodies have a base layer and a columnar structure positioned directly in front of or on the base layer. The columnar structure has a non-symmetrical distribution of height and cross-section, thereby forming a wide-band tuned moderator gap and the columnar height corresponds approximately to the density of the base layer. The columnar structure has a framework resonance adjustable as a function of parameters of the base layer.

Structured molded parts for sound absorption

A plate-shaped constructional element comprises a perforated plate made of a solid material such as metal, wood, wood chip board, pressboard, synthetic material or gypsum, and is characterized by the provision that a micro-perforated sheet or thin plate is disposed on one of the plate surfaces of the plate. One variant provides that the holes in the plate are formed in such a manner that they open each into a micro hole on one side of the plate.

Plate-shaped constructional element and method

A reactive sound attenuator which includes a sensor for detecting a sound parameter in a space, e.g. a duct, consists of a signal amplifier that is used to amplify a detected signal, an electroacoustic transducer and a cavity with at least one membrane. The membrane, which is capable of moving in a vibratory manner, is part of a wall of a space, e.g. a duct wall. A sensor, which is disposed in the immediate vicinity of, in or on the membrane, detects the vibrations of the membrane. The sensor's signal, which is amplified and inverted by the amplifier, controls the membrane vibration via the electroacoustic transducer.

Reactive sound absorber

A low reverberating room for the entire auditory range. In particular, for ow frequency ranges below 100 Hz, in which the walls and ceiling are covered with sound absorbers. The sound absorbers on a surface of about 70-90% of a room, not including the floor, have a depth of &lt;0.5 m preferably &lt;0.3. The sound absorber also has a closed, plane but acoustically permeable surface, are built up of multiple layers. The sound absorbers are about 20-70% in similarity to composite-plate resonators. They are also provided with inside plates, made of metal or heavy foil, which are designed of varying thickness for absorption in various frequency ranges.

Anechoic room for the entire auditory range

Plate resonator

Foil sound absorbers

False ceiling

Sound-absorbing glass building component or transparent synthetic glass

An axial fan has an impeller provided with vanes and mounted in a flow duct. In or on the wall of the duct at least one port is arranged adjacent to the vane tips. The duct side the port is provided with a covering means having passages therethrough.

Axial fan

Sound attenuating box

Leaks in fluid conveying pipe-lines, in which the noise from the escaping uid at the position of the leak creates sound waves are detected by at least one sound sensor and, at a known distance from it, a sound reflector, both of which are in direct contact with the fluid. The sound sensor receives the directly incident sound waves, and also the reflected sound waves from the sound reflector. The received signals are evaluated using an autocorrelation function.

Method and apparatus for locating leakages in pipes and similar conduits

Growing community of inventors

Weil, Germany

Helmut V Fuchs