|Acoustics applied to the environment    |
In France, people consider noise as the most harmful pollution. A Motorway, a railway, an airport, a factory situated near dwellings are unbearable sound loads which could harm health by long term effects such as the increasing of blood circulation troubles, sleeping disorders...
Various standards – concerning vicinity noises, transport infrastructures, urbanism near airports, classified installations, amplified music displays, building work area - limit the noise generated in the environment or define protection solutions.
Each project must take into account the adapted standard to define its acoustic constraints. The modelling allows the simulation of situations and the incidence of a technical solution on the sound impact of the project. They make it possible to define a long term strategy of noise reduction in the environment. Measurements also play a significant part in this field, because they make it possible to identify the various noise sources in the environment and/or to carry out a continuous monitoring.
Vicinity noises : Vicinity noises are numerous: land mowers, domestic animals, building equipments, trade murmur, etc... The French standard defines values for the emergence of maximum noise disturbance, compared to residual noise levels, by taking its duration into acount.
Transport infrastructures are the principal sources of harmful effects. The French standard defines not only the maximum noise level which can generate a new way ( in day and in night period ) but also the performance of insulation to provide for constructions (i.e. houses or schools) according to their distance to the new project.
Aerodromes : although technology made it possible to considerably reduce the noise emission from aircrafts in the last decades, the increasing air traffic amplified the inconvenience in the surroundings of the airports. The standards defined government assistance improvement of houses in airport area.
Classified installations : In France, most industrial facilities are subjected to the decree of January 23rd 1997 which is relative to the limitation of noise emitted in the environment by classified installations, for the protection of environment. This decree defines the acceptable maximum emergence in the industrial facility compared to the residual noise level (existing noise, before the industrial facilities construction). The emergence varies according to the period of the day, night or weekend.
Forecasts - modelling: the acoustic analysis phenomenon is facilitated by an adapted data modelling process which matches each case. This allows material and dimensional project characteristics (buildings and area topography) to predict the noise level, the quality of sound listening in buildings and in the environment, as well as the impact of noise reduction devices.
Amplified music: the French decree the 15th of December 1998 fixes the acoustic constraints of the diffusion of the amplified music. An insulation level between the diffusing music place and the residential place must be respected; it corresponds to the limit acceptable emergence. This decree also protects the users of such amplified music place; indeed it sets a limit average level in accessible public zones with 105 dB(A).
Continuous monitoring: progression has advanced with regards to data acquisition, which makes it possible to carry out continuous monitoring of the acoustic and vibratory phenomena. This is remotely controllable with modem acquisition system, which enables to acquire one or more uninterrupted signals for analysis and to switch on alarms (sound or optical) on predetermined thresholds in the form of a total level or a spectral gauge.
Measurement: acoustic and vibratory measurements constitute an essential means to carry out the situation diagnosis. They make it possible to characterize environment and listening quality of a room, home or work place comfort, embarrassment or machine noise emission... Accord Acoustique is very well equipped with powerful measurement instruments: level of acoustic pressure, intensimetry, vibratory analysis...