Auralization

Quantitative indicators that are traditionnaly used in the world of acoustics (typically sound levels in decibels) are most of the time too simple to actually assess a soundscape. They are also difficult to understand for non-experts, despite the fact that those non-experts make the majority of people exposed to noise in urban areas or inside buildings.

Auralization - which is the 3D restitution of soundscape in virtual environments - addresses this issue by recreating that a receiver would hear. This tool allows to make someone assess the quality of a soundscape by listening, as opposed to assess it with one single number, and also to quantify more precisely the characteristics of a given soundscape, way beyond the average level (emergence phenomena, ...).

Thanks to several decades of research, CSTB's experts have acquired a large know-how on the topic of soundfield restitution in complex domains, based on physical simulation (which takes into account the influence of the environment) coupled to powerful spatialization algorithms and innovative sound synthesis methods which allow to recreate in real time many different sources of noise.

 

Auralization tools

All CSTB technologies about auralization have been integrated within two complete simulation tools, with two main scopes:

 

Expertise

Three distrinct areas of expertise are necessary in order to virtually recreate a soundscape in a realistic manner:

  • noise source synthesis

One first needs to recreate the signal emitted by a source, which may vary as a function of parameters such as vehicle speed or engine regime.

  • propagation between source and receiver

Propagation takes into account the influence of the environment surrounding the source and the receiver: reflections on surfaces, attenuation due to a noise barrier, etc.

  • spatialization

Finally, one needs to restitute for a listener the impression that the noise - or one of its reflections - comes from a certain direction. This is necessary to recreate the 3D aspect of listening. Spatialization usually requires a designed restitution system (headphones or a set of ldistributed loudspeakers).

It is thanks to its expertise in these three domains that the CSTB has been able to create complete restitution tools such as MithraSON and AuralIES.

 


Noise source synthesis

For urban applications, CSTB has had to develop synthesis methods for different ground transportation sources such as tire rolling noise, car engine noise or tramway noise. These sources can be restituted very efficiently and very rapidly (which is paramount for real time restitution) thanks to an innovative patented method based on granular synthesis.

However, this method can also be appplied to other transportation noise sources as well as industrial noise sources. Here are a few examples:

Contact

Julien MAILLARD 

Tél : +33 4 76 76 25 28

Email : julien.maillard@remove-this.cstb.fr