As signals travel, they become weaker. This is as true with sounds traveling through air as it is with electrical signals traveling through wires. Attenuation is usually represented as a loss of decibels (dB). Other factors in the construction of cables make higher frequencies attenuate greater ("high frequency attenuation"). Cables, as listed in the Belden catalogs, intended for carrying signals, will show a list of frequencies and the loss at that frequency per standard length (100 ft. or 100 m) so that the performance of similar cables can be compared.