Real-time auralization of propagation paths with reflection, diffraction and the Doppler shift
* Presenting author
The auralization of early reflections is often implemented using digital signal processing and steady-state filtering by assembling multiple propagation paths into a single filter. To render the Doppler shift in interactive auralization systems audible, the constraint of linear and time-invariant filtering must be dropped. Instead, resampling during real-time audio processing must be performed. Especially in urban outdoor scenarios, it is not only necessary to account for time variant movement of fast sound sources, but also for dynamics of the built environment. Consequently, if specular reflections and diffraction paths should be considered for real-time auralization, a combination of resampling and filtering must be deployed. A single-input multiple-output variable delay line (SIMO VDL) is suggested to effectively create the Doppler shift for early reflections and to prevent comb filter effects during filter exchange. It consists of multiple interpolating read cursors and subsequent short filtering modules that apply individual spectral attenuation effects caused by medium propagation and boundary interaction.