Hi Marc, Yes, as with SMAs, the aliasing frequency scales inversely with the radius.
But a small radius limits the low-frequency end: The smaller the radius is, the higher will be the frequencies above which a certain (higher) order can be deduced. The 0th order is always there. For an array with a very small radius the 1st order may only be available above a certain frequency (and up until the aliasing frequency) etc. The radius of this particular prototype had a very different motivation: We figured out that there existed only about half a dozen arrays in the world that use this equatorial layout, and all of them were experimental prototypes. The one that we used in the video was originally built for motion-tracked binaural where the array needs to have a radius similar to that of a human head so that a useful ITD is produced. Here are the details of the array: https://www2.ak.tu-berlin.de/~akgroup/ak_pub/abschlussarbeiten/2018/Fiedler_MasA.pdf Fortunately, this is indeed a size that allows for fitting all hardware into the scattering body. It is certainly no coincidence that this same size works well also for SMAs that perform spherical harmonic decomposition for subsequent binaural rendering. Many authors concluded this. One author that I can remember off the top of my head is Benjamin Bernschütz. His PhD thesis contains a lot of information on this. If it works well for SMAs, then it works well for EMAs! It was indeed a bit of luck that we were able to get hold of a prototype that was ideal for our purposes. In the near future, we will look into how small the array can be before things break down. Best regards, Jens On 1 Dec 2021, at 15:55, Marc Lavallée <[email protected]<mailto:[email protected]>> wrote: Le 2021-12-01 à 09 h 20, Jens Ahrens a écrit : I’m not sure if I understand your question correctly. I’ll do my best to be comprehensive so that my response covers what you are interested in: For this type of array, the spatial aliasing frequency f_a is dependent on order N and radius R of the array in the exact same manner like with spherical microphone arrays (SMAs): N = (2 pi f_a / c) R N = 7 R = 0.0875 m So that f_a = 4.3 kHz With a bit of algebra, f_a = c N / ( R 2 pi ). So a smaller radius for the sphere would improve f_a? Was 0.0875 m chosen in order to embed some hardware? Marc -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20211201/c59791e6/attachment.htm> _______________________________________________ Sursound mailing list [email protected]<mailto:[email protected]> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on. -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20211201/39467f1a/attachment.htm> _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
