| 摘要 |
The high frequencies of the train noise are damped very well on rails by means of ballast and other sound-absorption measures, but the low frequencies around 125 Hz are scarcely damped at all. In a tunnel, for example, the low frequencies are thus the dominating elements of the sound level. By means of suitably dimensioned openings in the cable duct adjacent to the rail, the duct is used as a Helmholtz resonator. Ducts with normal dimensions absorb this resonance effect for frequencies between 125 and 210 Hz. Thus, using the cable duct constructed according to the invention, the sound emitted from railway rails can be considerably reduced, particularly in the low frequency band.
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