## 1 Introduction  
The Sustainable Development Goals are a universal call embraced by all Member States of the United Nation in 2015 for eradicating poverty and protecting the environment. According to the call, for improving the living condition on a global scale, economy and social aspects must go hand-in-hand. For this reason, issues such as education, health, social protection, job opportunities, climate change and environmental protection must be taken into account through global, local and people actions [1]. Among the 17 Goals, number 11 deals with sustainable cities and communities, and it requires to ensure access for everyone to adequate, safe and affordable housing and basic services. Indeed, it is estimated that by 2030 the 60% of the world's population will live in cities that account for about the 70% of global carbon emission and 60% of resource use. The rapid urbanization that the world has been facing since 2007 is resulting in air pollution, unplanned urbanization, inadequate services and infrastructures. The growth and development of cities must be controlled, so to guarantee cities inclusive, safe, resilient and sustainable. Since people with similar socioeconomic status tend to cluster in the same urban areas disadvantaged contexts can be easily identified in the urban fabric: in these places, the vulnerable population lives and it consists of refugees, migrants, elderly persons, people with disabilities and children [1]. In these specific contexts, people live below the threshold of poverty, and sometimes in conditions of great discomfort. This phenomenon is responsible of inequalities and it has been identified in several European cities, as in the case of Barcelona [2; 3]. Between 2001 and 2011, in the city of Barcelona the migrant population increased from about 5% to 17%, and the new-low income immigrants reside mostly either in the historical center, usually on degraded 19 th century buildings, or in peripheral districts characterized by poor quality houses built in the 1960s and in the 1970s [2]. In the case of the historical center, dwellings are in some cases small, overcrowded and lacking of openings with consequent insufficient natural light and poor air quality. When present, windows are crumbling and do not guarantee adequate acoustic insulation. Since many of these neighborhoods are also touristic destinations with noisy anthropic activities also during the night-time, the aspect related to the sound quality of dwellings should not be underestimated. The urban environment is characterized by multiple simultaneous sounds due to transportation, industry and neighbors. When the sound pressure level exceeds a certain value it is perceived as noise and even if sound perception is subjective, noise control is very important. The exposure to excessive and prolonged levels of noise affects people's well-being, behavior, productivity, mental and physical health, with negative consequences such as sleep disturbances, stress, irritability and other health issues [2; 4; 5; 6]. However, noise pollution and acoustic discomfort in buildings are not limited to disadvantaged neighborhoods. To depict the acoustic situation, the European Union, through the Environmental Noise directive [7], has requested to map the noise pollution sources and to define an action plan to reduce the effects on the population. It is estimated that 40% of the population does not experience acoustic well-being because of noise from neighbors and traffic [5], and the 65% of Europeans living in major urban areas are exposed to high-noise levels [8]. If in virtuous contexts the improvement of the indoor acoustic comfort is possible, in disadvantaged contexts this task is much more difficult to achieve. In fact, these interventions require specialized personnel and expensive insulating/absorbing acoustic solutions. Acoustic panels must be aesthetics, safe, acoustically efficient, easy to install and maintain, resistant to wear and environmental factors.