One of the foremost challenges we face in conservation is understanding how effective different conservation strategies are. Such effectiveness, especially in terms of biodiversity conservation, can be very difficult to measure, time consuming, and prone to many different biases. Bioacoustics, and specifically the recording and analysis of entire soundscapes, could be a suitable tool for monitoring animal biodiversity in the conservation areas as well as sustainably managed forests. I will show three examples of bioacoustics projects from tropical forests in Papua New Guinea and Indonesia, to illustrate the potential as well as the limitations of this new, promising conservation technology.