This invention relates to a system (100) and method for selecting a signal processing program to be executed by a signal processor in a hearing aid. The system (100) comprises a single layer of neurons (200) each having one or more neighbours and being arranged in a memory device (106), wherein each neuron comprises a neuron vector referring to a specific acoustic situation and a neuron label referring to signal processing program associated with said specific acoustic situation. The system (100) further comprises a sensor adapted to detect an external acoustic situation and to define a sensor vector associated with said external acoustic situation, and wherein a processor (102) calculates a vector difference between said sensor vector and each of the neuron vectors, identifies that neuron providing the smallest vector difference, and selects a signal processing program referred to by a neuron label of that neuron.