Spatial Upsampling of Head-Related Impulse Responses via Elevation-Wise Encoder-Decoder Networks

A method for performing spatial upsampling of Head-Related Impulse Responses (HRIRs) from sparse measurements is introduced. Based on a supervised elevation-wise encoder-decoder network design, we present two variants: one that performs progressive reconstructions with feed-forward connections from higher to lower elevations, and another that excludes these connections. The variants were evaluated in terms of the errors in interaural time and level differences, as well as the spectral distortion in the ipsilateral and contralateral ears. The additional complexity introduced by the variant with feed-forward connections does not always translate into accuracy gains, making the simpler variant preferable for efficiency. Performance generally improved as the number of available measurements increased. However, accuracy was also found to strongly depend on the spatial distribution of those measurements. Compared to an average non-personalized HRIRs, interaural time differences remain similar, while the proposed method achieves higher spectral and level accuracy, highlighting its practical use for HRIR upsampling.