1/f Noise in Rural and Urban Soundscapes

In complex systems, log-log linear relations between appropriate descriptors are quite common. In this paper, the rural and urban soundscape is assumed the voice of a complex system. Self-organized criticality is shown to occur at different levels in this underlying system. The power spectral density of loudness and pitch in recordings of rural and urban soundscapes indeed often follows quite closely to the typical 1/f frequency dependence in many cases. Looking in detail at the data, a breaking point is observed in many of the curves around 0.2 Hz, which corresponds to a period of 5 seconds. It seems logical to associate this to within event and between event sound dynamics. Indicators based on this analysis could be useful for cataloguing soundscape dynamics. By extension of the earlier finding that 1/f noise is quite common in music, labels such as "boring / dull" or "too chaotic / too unpredictable" may even be borrowed to describe soundscape dynamics.