Low cost (audio) recording (LCR) for advancing soundscape ecology towards the conservation of sonic complexity and biodiversity in natural and urban landscapes

Low cost (audio) recorders (LCRs) represent a new opportunity to investigate the sonic complexity of both natural and urban ecosystems. LCRs are inexpensive sampling audio recorders which have the external shape of a universal serial bus (USB) flash drive, and are composed of a microphone, an analog-to-digital converter, central processing unit with permanent internal non-volatile memory, rechargeable battery, and a USB connection. The reduced dimensions allow the device to be deployed inconspicuously within any environment, in any configuration and for an extended time period. This investigation tested a specific type of LCR (UR-09) with a spectral range of 8 kHz - sufficient to cover the acoustic range of most western Palearctic songbirds. The reliability of the UR-09, compared with other commercial recorders (Zoom H4 and Song Meter SM1) and based on the quality of recordings quantified by the Acoustic Complexity Index (ACI), was tested and confirmed. An example of the application of LCRs is presented in an evaluation of the audio patterns occurring during dawn and dusk choruses within a forested ecosystem. Results of this investigation are encouraging and a new generation of LCR devices is currently being designed with real-time acoustic data processing capabilities, timer programmability, a larger frequency range and wireless communication compatibility. LCRs are revealed to be ideal instruments to conduct surveys in fragile or protected areas and also in urban environments. Moreover, due to their low cost, they can be used to encourage research in soundscape ecology, especially within developing countries, where large areas can be monitored by professionals or incorporating citizen science models of data collection.