I. Introduction
Environmental noise is one of the most critical risks for population health and well-being. The World Health Organization has recently remarked that noise affects at least 100 million people, only in the European Union [41]. Generally, sound level monitoring and control are the common tools for managing the acoustic environment and sound quality remains dismissed. However, noise abatement is often unavailable or unsuitable in certain scenarios like cities, or does not necessarily result in an approving appraisal of final soundscapes [39]. Hence, “quiet areas” are a new perspective that focuses on the acoustic quality more than on the sound level, and which are being even regulated in the European Union [3].