Why a new index?
There is a demand from the general public and the authorities for easier-to-understand information about environmental noise.
The creation of the strategic noise maps required by European directive 2002/49/EC has initiated a new dynamic with environmental noise being taken into account by the authorities and the public being provided with more information on the subject.
Certain local authorities have also promoted the development of noise measurement networks (Madrid, Brussels, Athens, Greater Lyons, Lille, Paris and the Ile-de-France region, etc.) to provide decision-makers with reliable information about noise levels and thereby more effectively guide public policies for fighting noise pollution. Carried out alongside noise mapping, and more accurately reflecting the reality of perceived noise, noise measurement helps to make a more accurate diagnostic, to provide information about variations in noise levels throughout the day, and to identify specific events like car horns, and the passage of noisy aircraft, trains, and motor vehicles.
Nevertheless, whether the information about noise is presented in the form of strategic noise maps or in the form of measurement results, it currently remains difficult for laypeople to understand because of the many indicators used (Lden, Ln, LAeq, LA10, LA90, NA, and LAmax, to name just a few), which are complicated to explain and relatively far-removed from inhabitants' perception. Furthermore, the unit used by these indicators - namely the decibel - has the disadvantage of being complex, with the addition of two noise levels expressed in decibels being logarithmic rather than arithmetic. For example, 60 + 60 dB is not 120 dB but 63 dB...
All these reasons make it even more difficult for the authorities and the general public to take ownership of the noise issue.
A survey of 800 people was conducted at the beginning of the Harmonica project, in order to evaluate the general public's current level of knowledge and expectations in terms of information on the noise environment. The results obtained confirmed the idea that the public has difficulty understanding the information currently provided about noise. The survey confirmed that respondents' understanding of acoustics is very fragmented and that they have difficulty estimating noise levels of everyday events and situations. The survey also revealed that the public believes that information about noise peaks that occur during the day would effectively complement the measurements of noise levels.
It was therefore becoming essential to provide information that is easier to understand and more closely reflects the reality of noise nuisances as they are perceived by the public.
That was the objective behind the project to create the Harmonica index.