9. A method of speech enhancement using a Neural Network based combined signal comprising: training a neural network offline, wherein training the neural network offline includes: exciting at least one accelerometer and at least one microphone using a training accelerometer signal and a training acoustic signal, respectively, wherein the training accelerometer signal and the training acoustic signal are correlated during clean speech segments, selecting speech included in the training accelerometer signal and in the training acoustic signal, and spatially localizing the speech by setting a weight parameter in the neural network based on the selected speech included in the training accelerometer signal and in the training acoustic signal; and generating by the neural network a speech reference signal based on an accelerometer signal from the at least one accelerometer and an acoustic signal received from the at least one microphone.
10. The method of claim 9 , wherein the neural network provides spatial localization of features, weight sharing and subsampling of hidden units.