1. Method for accelerating neural network ( 4 ) execution in a speech recognition system, for recognising words contained in a subset of a general vocabulary of words that the same system is capable of recognising, said neural network ( 4 ) comprising a number of computing units organised in levels, among which at least one hidden level ( 12 ) and one output level ( 14 ), the computing units (H j ) of said hidden level ( 12 ) being connected to the computing units (N i ) of said output level ( 14 ) via weighted connections (W ij ), said computing units (N i ) of said output level ( 14 ) corresponding to acoustic-phonetic units ( 2 ) of said general vocabulary, characterised in that it comprises the following steps: determining a subset of acoustic-phonetic units necessary for recognising all the words contained in said general vocabulary subset; eliminating from the neural network ( 4 ) all the weighted connections (W ij ) afferent to computing units (N i ) of said output level ( 14 ) that correspond to acoustic-phonetic units not contained in said previously determined subset of acoustic-phonetic units, thus obtaining a compacted neural network ( 4 ′) optimised for recognition of the words contained in said general vocabulary subset; executing, at each moment in time, only said compacted neural network ( 4 ′).