3 research outputs found
Individual Listening Zone with Frequency-Dependent Trim of Measured Impulse Responses
Acoustic Contrast Control (ACC) has been widely used to achieve individual audio delivery in shared environments.
The effectiveness of this method is reduced when the control is performed in reverberant environments. Even if
control filters are computed using measured transfer functions, the robustness of the system is affected by the
presence of reverberation in the plant matrix. In this paper a new optimization method is presented to improve the
ACC algorithm by applying a frequency-dependent windowing of the measured impulse response used for the filter
computation, thus removing late reflections. The effects of this impulse response optimization are presented by
means of sound zoning results obtained from experimental measurements performed in a car cabin
Virtual Reality for Subjective Assessment of Sound Quality in cars
Binaural recording and playback has been used for decades in automotive industry for performing subjective
assessment of sound quality in cars, avoiding expensive and difficult tests on the road. Despite the success of this
technology, several drawbacks are inherent in this approach. The playback on headphones does not benefit of
head-tracking, so the localization is poor. The HRTFs embedded in the binaural rendering are those of the dummy
head employed for recording the sound inside the car, and finally there is no visual feedback, so the listener gets
a mismatch between visual and aural stimulations. The new Virtual Reality approach solves all these problems.
The research focuses on obtaining a 360° panoramic video of the interior of vehicle, accompanied by audio
processed in High Order Ambisonics format, ready for being rendered on a stereoscopic VR visor. It is also
possible to superimpose onto the video a real-time colormap of noise levels, with iso-level curves and calibrated
SPL values. Finally, both sound level colormap and spatial audio can be filtered by the coherence with one or
multiple reference signals, making possible to listen and localize very precisely noise sources and excluding all
the others. These results have been acquired employing a massive spherical microphone array, a 360° panoramic
video recording system and accelerometers or microphones for the reference signals
Individual listening zone with frequency-dependent trim of measured impulse responses
Acoustic Contrast Control (ACC) has been widely used to achieve individual audio delivery in shared environments. The effectiveness of this method is reduced when the control is performed in reverberant environments. Even if control filters are computed using measured transfer functions, the robustness of the system is affected by the presence of reverberation in the plant matrix. In this paper a new optimization method is presented to improve the ACC algorithm by applying a frequency-dependent windowing of the measured impulse response used for the filter computation, thus removing late reflections. The effects of this impulse response optimization are presented by means of sound zoning results obtained from experimental measurements performed in a car cabin