an apparatus and system for recognizing touch positions is comprised of multiple acoustically coupled substrates , said coupling functioning also as an environmental seal . at least one secondary substrate , with means to transmit and receive acoustic waves , is coupled to a primary substrate capable of propagating acoustic waves such that an intentional touch on the surface causes a perturbation of the waves passing through a desired region of touch detection . said perturbation is analyzed by circuitry to determine corresponding physical position of the touch on surface