IMMI 2021 with level-faithful auralisation tool - How does your forecast actually sound?

With the 2021 update, we will publish the first level-true auralisation algorithm for noise on the market for IMMI. The basic idea is to make sound immission predictions audible, on the one hand to make calculation results more clear to people outside the field, and on the other hand to allow IMMI users to explore their models via the sensory organ of the ear.


The auralisation tool will support road traffic noise and stationary commercial noise in the first step. The auralisation of road traffic noise is based on road location, traffic counts and speeds. Using signal processing methods, the software enables the user to experience stereo effects, Doppler effects and shielding in a spatial and temporal context, in addition to the usual distance-dependent attenuation terms.

Realistic auditory impression through integrated, expandable audio database

By means of a simple calibration procedure, the output via any loudspeaker is true to level, i.e. for the audio signal, which is always calculated on a one-minute reference time, the same average level results as for the calculation method chosen in the forecast calculation at the place of immission. To enable a more realistic auditory impression, the audio signals can be supplemented with background noise, which is available in a database or can also be added from own measurements. In addition, insulation spectra of windows can be mapped in the auditory impression.

How do ISO9613-2 and CNOSSOS-EU sound?

For us as the IMMI team, the development of the auralisation tool was a valuable experience, because after more than 30 years of development work on a software for sound propagation calculation, we were able to hear for the first time how our predictions sound. You will be surprised how different the rules sound for one and the same situation - for us, the good old ISO9613-2 has proven to be an acoustically valid prediction calculation, in contrast to CNOSSOS-EU, which sometimes provides questionable artefacts, especially for special obstacle situations.

We hope you will enjoy this new development as much as we do! The auralization tool was released with the IMMI update 2021-02 in early August and can be downloaded by IMMI users in the login area here.

>> You are not yet an IMMI user? Then learn more about our software for immission control here <<

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