Environmental pollution is likewise characterized by noise emissions. As a result, according to the European ambient noise directive 2002/49/EG, noise pollution of inner-city areas, in particular congested urban areas, is a major issue of the future European policy. In areas of bus stops and roofed installations, such as bus stations, there are high values of disturbing noise emissions induced by urban bus traffic.Concerning this matter, hybrid urban buses are able to offer promising solutions for an effective noise emissions reduction. At the Institut für Kraftfahrzeuge (ika), RWTH Aachen University, the project "HYBOB," financed by the BMWi (Bundesministerium für Wirtschaft und Technologie), is being conducted in cooperation with the EvoBus GmbH/Daimler Buses. The project is aiming to design and develop a highly sophisticated serial-hybrid diesel-electric propulsion system for urban bus applications. Besides fuel consumption reduction and lower CO2 emissions, the development and implementation of innovative solutions for an effective noise emissions reduction and also enhanced passenger comfort are major NVH-related tasks of this project. Relevant NVH aspects, the development process as well as current optimization results of the ongoing project are represented in this paper.