André, M., van der Schaar, M., Zaugg, S., Houégnigan, L., Sánchez, A.M., Castell, J.V. Listening to the Deep: Live monitoring of ocean noise and cetacean acoustic signals Marine Pollution Bulletin, vol 63, p.18-26, 2011 Abstract: The development and broad use of passive acoustic monitoring techniques have the potential to help assessing the large-scale influence of artificial noise on marine organisms and ecosystems. Deep-sea observatories have the potential to play a key role in understanding these recent acoustic changes. LIDO (Listening to the Deep Ocean Environment) is an international project that is allowing the real-time longterm monitoring of marine ambient noise as well as marine mammal sounds at cabled and standalone observatories. Here, we present the overall development of the project and the use of passive acoustic monitoring (PAM) techniques to provide the scientific community with real-time data at large spatial and temporal scales. Special attention is given to the extraction and identification of high frequency cetacean echolocation signals given the relevance of detecting target species, e.g. beaked whales, in mitigation processes, e.g. during military exercises. Project: LIDO, Listening to the Deep-Ocean Environment Project: ESONET, Network of Excellence Project: NEPTUNE Canada, Data from the Deep – Judgements from the Crowds - CANARIE Project NEP-67