The BYU Acoustics Research Group, with funding from the National Science Foundation, has investigated a new control parameter known as WSSG (weight sum of spatial gradients). WSSG has shown great promise of providing control. Results on plates have proven to be significantly better than with volume velocity.
Please see the attached papers for additional information:
P. Aslani, S. D. Sommerfeldt, and J. D. Blotter, “Active control of simply-supported cylindrical shells using the weighted sum of spatial gradients control metric,” Journal of the Acoustical Society of America, Vol. 143, No, 1, pp. 271-280 (2018).
Y. Cao, S. D. Sommerfeldt, W. Johnson, J. D. Blotter, and P. Aslani, “An analysis of control using the weighted sum of spatial gradients in active structural acoustic control for flat panels,” Journal of the Acoustical Society of America, Vol. 138, No. 5, pp. 2986-2997 (2015).
D. R. Hendricks, W. R. Johnson, S. D. Sommerfeldt, and J. D. Blotter, “Experimental active structural acoustic control of simply supported plates using a weighted sum of spatial gradients,” Journal of the Acoustical Society of America, Vol. 136, No. 5, pp. 2598-2608 (2014).