Dear MarMam colleagues, We would like to invite individuals and organizations with an interest in passive acoustic monitoring (PAM) of marine mammals to collaborate on the development and testing of a new browser-based app called "Orcasound." This is a evolution of the 15+year-old Salish Sea Hydrophone Network -- orcasound.net <http://orcasound.net?5050mm> -- based in WA, USA. If successful this project will at least make it much easier for citizen scientists to use their favorite device to listen for whales. At the most it will juxtapose in a spirited scientific competition two distinct approaches to bioacoustic analysis (e.g. detection, annotation, classification): crowd-sourcing through citizen science networks and algorithms run on high-performance computers in the cloud. The initial goal of the app is to streamline listening to live or recorded audio. It also enables listeners to report when they hear something interesting and to be notified of acoustic events detected by the network. After testing and refinement of these fundamental features (listening, detecting, notifications) the stage will be set for annotation and classification experiments (c.f. bioacoustic citizen science projects, Bat Detective <https://www.batdetective.org/> and WhaleFM <http://whalefm.org>). If you would like to collaborate, please don't hesitate to contact us. We are interested in discussing the project with marine mammal specialists who have deployed hydrophones, steward acoustic data archives, or have implemented bioacoustic detectors, classifiers, and/or citizen science projects. We would also like to invite educational/outreach organizations with an interest in marine mammal sounds and ocean noise pollution to join the current Hydrophone Network members in freely creating and sharing resources. If you know any audiences who would benefit from receiving notifications of live or recorded listening options (e.g. docents or interpreters teaching about soniferous species or noise pollution), we would appreciate you inviting them to join our Network so that they can influence the development of the Orcasound app. Looking foward to hearing from you, Scott and Val Veirs