1. A method of sound spatialization with a multichannel encoding and for reproduction on two loudspeakers, comprising a spatial encoding defined by encoding functions associated with a plurality of encoding channels and a decoding by applying filters for reproduction in a binaural context on the two loudspeakers, comprising: a) obtaining an original suite of acoustic transfer functions specific to an individual's morphology, each transfer function in said original suite of acoustic transfer functions being associated with a position in space; b) choosing, on the basis of at least one criterion of reduction of calculation complexity, to fix at least one of spatial encoding functions or decoding filters, and c) through successive iterations, optimizing the filters associated with the chosen encoding functions fixed in b) or the encoding functions associated with the chosen filters fixed in b), or jointly the chosen filters and encoding functions, by minimizing an error calculated as a function of a comparison between: the original suite of acoustic transfer functions, and a suite of transfer functions reconstructed on the basis of the encoding functions and the decoding filters, optimized and/or chosen, wherein the comparison in c) is calculated by, for each position in space associated with a transfer function in said original suite of acoustic transfer functions: computing a first value being a moduli of said transfer function in said original suite of acoustic transfer functions; computing a second value being a moduli of a transfer function in the suite of reconstructed transfer functions; computing differences between the first value and the second value, expressed in the frequency domain and time independent.