Abstract: A method and apparatus is taught for a signal processing breakthrough that significantly alleviates the “Curse of Dimensionality” (COD) in the characterization of nonlinear physical systems; namely, the reduction in the number of coefficients used to describe the higher order (i.e., nonlinear) kernels in the Volterra series expansion. The latter technique provides the means to evaluate simultaneously from a wide band excitation, all the inter-modulation products up to a specified order by greatly reducing the number of coefficients in the higher order kernel estimation to a manageable set that can be easily manipulated by current personal computers used to enhance a finite element (FE) model that generates a bio-inspired acoustic transducer model.

Abstract: A training aid for skaters includes an enlarged block made from a soft resilient material and including an elongated exterior wall which has an upwardly facing exterior surface. An arrangement is provided for permitting removable support of the block on the skater's torso with the exterior wall projecting from the skater's neck below and significantly forwardly beyond the skater's chin with the exterior surface positioned closely adjacent and below the skater's chin. The resilient block is made from a material which is sufficiently opaque to obstruct normal vision therethrough, thereby obstructing the skater's vision of his skates and a portion of the ice immediately forwardly thereof.