Since it is Christmas time, Creo Dynamics has made a study of Santa Clause’s acoustic strategy when he’s delivering the Christmas gifts; – We now start to understand why you can’t hear him!
The case is this – He’s using the cutting-edge tools for passsive and active sound control.
Mr Clause is probably using a set of unique Acoustic Perturbation Equations based on a Lattice-Bolzmann solver for simulating the sound propagation when the sleigh is approaching and entering the chimney. The simulation is then used to estimate the sound going from the sleigh to the chimney, as well as through the chimney flue into the cavity (i.e. your living room) – Well, Santa is probably not limited by the F1 Team’s 25 TeraFLOPs per season to enable the required models – The above, combined with a full spatial matching of the primary acoustic field in the cavity (i.e. he’s listening to the sound in your living room), helps him to calibrate;
a) the damper-liner pipe, made by 3D-printed Helmholtz resonator metamaterial, that he uses inside the chimney to reduce the tonal noise generated when going in and out of your living room through the chimney,
b) the parameter settings of the portable broad-band active noise control system he uses when inside your living room, based on low-frequency sub-band FXLMS algorithms, and activated by piezoelectric panels on the sleigh (which he also uses as speakers when listening to Bing Crosby between the visits).
The noise simply disappears!
How we “guess” all this? Well… this is what we do every day at Creo Dynamics, and sometimes we have very prestigious clients…