Sound-absorbent edges have been the subject of experiments for many decades. Forster has now pioneered a clear solution based on the law of physics and using an efficient combination of computer simulations and standardised experiments – the FONOCON sound resonator. An acoustically effective cap optimised specifically for the noise spectrum of railways, the FONOCON can be used on existing as well as newly built noise barriers.
Drawing on scientific partners that provide the acoustic expertise, it is now possible to obtain clear information on the actual effectiveness and assign such data to the relevant European standards. The accoustic effect is a major factor in rating the effectiveness of a resonator which Forster has efficiently and compatibly harnessed to the design of its noise protection system. In terms of factors such as acoustics, design and functionality, the FONOCON sound resonator is a unique innovation.
The acoustic concept underlying the top edge system is based on λ/4 resonators. These resonators which are closed on one side, cancel the noise pressure of the resonance frequency at apetures of the resonator chambers due to destructive interference.
In order to optimise the FONOCON Sound-Resonator, the lengths of the resonator chambers have to be adapted to the ultimate use.
In addition to optimising noise diffraction, there are at least two more aspects that help reduce the noise: the projecting edge of the system (compared to the remaining noise barrier) and the geometric alingment of the absorption area.