An artificial neural network is disclosed that processes holography generated characteristic patterns of vibrating structures along with finite-element models. The present invention provides for a folding operation for conditioning training sets for optimally training forward-neural networks to process characteristic fringe patterns. The folding pattern increases the sensitivity of the feed-forward network for detecting changes in the characteristic pattern. The folding routine manipulates input pixels so as to be scaled according to the location in an intensity range rather than the position in the characteristic pattern.