Soundecology indicators applied to urban soundscapes

In remote ecological monitoring studies the characteristics of the soundscape is one of the key aspects in the assessment of the ecological environment. In order to characterize these natural soundscapes different acoustic indices are currently under study: the bioacoustic index, the acoustic complexity index, the acoustic diversity index, the acoustic eveness index and the normalized difference soundscape index. These indices reflect in part the nature of the different sounds present in the soundscape. As an example the acoustic complexity index is known to correlate with the number of bird vocalizations in the environment, while it is insensitive to airplane noise. In general, the indicators could reveal the balance between biophony, geophony, and anthrophony in the natural soundscape. Starting from urban sound recordings the different acoustic indices are calculated. In this way the resulting temporal character of the acoustic indices is obtained and can be related to the activity level in the biophony, geophony or anthrophony of the urban environment. The results show that soundecology concepts can be applied for soundscapes more strongly governed by noise.