While used in routine for fish biomass assessment in a variety of marine laboratories, underwater acoustics have an unrealized potential for multi-component observations of abiotic and biotic ecosystem characteristics. A growing number of studies is taking advantage of recent improvements (e.g. multifrequency, broad band echosounders) to simultaneously characterize physical structures (e.g. thin layers, internal waves, eddies) and organisms (from zooplankton to whales) patterns of distribution across scales from meters to thousands of kilometers. These progresses open a variety of perspectives for understanding complex processes. In this context, the aim of this short note is twofold: (i) provide examples of the application of 'ecosystem acoustics' to describe and quantify complex processes; and (ii) present the current advances and perspective of the application of ecosystem acoustic in Northeast Brazil.