Sinusoidal modelling for ecoacoustics

Biodiversity assessment is a central and urgent task, necessary to monitoring the changes to ecological systems and under- standing the factors which drive these changes. Technological advances are providing new approaches to monitoring, which are particularly useful in remote regions. Situated within the framework of the emerging field of ecoacoustics, there is grow- ing interest in the possibility of extracting ecological informa- tion from digital recordings of the acoustic environment. Rather than focusing on identification of individual species, an increas- ing number of automated indices attempt to summarise acoustic activity at the community level, in order to provide a proxy for biodiversity. Originally designed for speech processing, sinu- soidal modelling has previously been used as a bioacoustic tool, for example to detect particular bird species. In this paper, we demonstrate the use of sinusoidal modelling as a proxy for bird abundance. Using data from acoustic surveys made during the breeding season in UK woodland, the number of extracted sinusoidal tracks is shown to correlate with estimates of bird abundance made by expert ornithologists listening to the recordings. We also report ongoing work exploring a new approach to investigate the composition of calls in spectro-temporal space that constitutes a promising new method for Ecoaoustic biodiversity assessment