Researchers at the Fraunhofer Institute for Structural Durability and System Reliability LBF and Darmstadt University of Technology have recently developed a new type of soundproof window. "The perceived noise indoors is only half as loud," says Dr. Thilo Bein, who manages the institute's department of energy, environment and health. "We have even been able to reduce the volume of certain test signals by up to 15 decibels." The experts have predicted a reduction of up to 10 dB for the engine noise of passenger aircraft in the frequency range below 1000 Hz.
A thin chip of piezoelectric material attached to the window counteracts the vibration by generating an oscillation at the same pitch but in the opposite sense to that measured by the sensor - causing the pane to move in the opposing direction. "We have devised a similar solution for the points where the outer cladding is attached to the frame of the building. In this case, a stack of piezoelectric chips, rather than a single piezoelectric strip, counteracts the impinging force," says Bein.
Source: transstudio.comAdded: 20 June 2007