The European Noise Directive 2002/49/EC (END) prescribed two new instruments for the management of environmental noise, to be updated every five years: Noise Maps (i.e. like photos of the existing noise in an area) and Action Plans (i.e. a collection of measures to reduce noise, where needed, and preserve acoustical quality, where it is already good). Both these instruments are based on population exposure, expressed by the yearly average of the acoustical energy impacting on a dwelling (measured in dBs).

At 7 years from the Directive, the first round of noise mapping (and two EU-funded research projects) have highlighted the practical limit of noise mapping exercises. Even with their large uncertainties, Noise Maps have in fact proven good to identify 'hot spots' (i.e. the areas where health risks due to noise exposure are non-negligible), but cannot tackle effectively with the annoyance of citizens, as they cannot describe it. The same terms 'noise' and 'positive sounds', in fact, have an implicit human judgement in them, which dB-based Maps cannot take into account. Resulting Actions plans, consequently, aim at reducing noise energy (dBs), without being able to improve/preserve the acoustical quality of an area: they have no means to measure when an area passes from 'bad' to 'good' in the perception of his inhabitants.

Investigating how we perceive noise and how to design perception-oriented action plans is then becoming more and more a priority for the acoustical community, as it will lead to more welcoming buildings and urban areas, to better-perceived parks, to futuristic cinemas and theatres (e.g. where the sound is customised to the single spectator's level), to areas designed for hearing-impaired people, to an overall increase in the quality of life.

In this context, researchers all over Europe are looking for specific indicators to bridge the gap between classical measurands and perception, looking for the means to design outdoor spaces like Roman architect Vitruvio designed theatres. Terms like 'soundscape' and 'acoustical comfort', at the border between the current measurement techniques and the land of perception, summarise a great part of their efforts.

Starting from noise mapping, this talk will briefly fly through 4 years of research into soundscape indicators, taking the audience on a possible practical path that starts from the definition of a new indicator and ends with the means for innovative Action Plans. To this aim, the studies on Sonic Gardens tested all through Europe, and the feasibility study for two different areas in Central London will be briefly presented in this talk.

Perspectives for new measurement techniques and the possibilities open by MEMS microphones will also be described.