"Reaching low levels of cabin and ramp noise is crucial to ensure the satisfaction of aircraft passengers and a safe working environment for the crew and personnel servicing the grounded aircraft. From the passenger and personnel standpoint, good thermal and acoustic comfort is important to minimize both stress symptoms and tiredness. Required to provide satisfactory air quality and temperature, the Environmental Control Systems (ECS) currently used are key contributors to the acoustic nuisance within the cabin and around the grounded aircraft. Reducing the amount of noise produced by the ECS will therefore have a direct impact on the passenger satisfaction and personnel health and safety.Unlike aircraft exterior noise, which has received considerable attention in past and currently running research projects, the noise emitted by confined flows in ECS assemblies involves complex mechanisms that haven’t been sufficiently investigated to permit the noise reduction wished by passengers and regulators. Acoustic and hydrodynamic interactions between subcomponents have so far been largely neglected despite being crucial.Thorough experimental studies will be conducted in order provide a deeper understanding of these mechanisms. A combination of accurate scale-resolved methods with low-CPU cost statistical/stochastic methods will then be proposed as an original modelling and design approach.Integrated passive flow and noise control strategies will be explored both experimentally and numerically. The knowledge gained in the experimental and numerical investigations of the installation effects will permit devising and optimise strategies having the best potential for reducing ECS noise.The best noise reduction strategies will be finally tested on a full-scale ECS system, and their impact towards improved passenger comfort and airport personnel health will be assessed with respect to the objectives of the Work Programme and relevant regulations."