The invention relates to a method for the conversion, encoding, decoding and trans-coding of a sound field, especially a first-order Ambisonics three-dimensional sound field, including at least one method of converting said sound field into a spherical field, a method of encoding said spherical field into a stereophonic signal, a method of decoding a stereophonic signal to a spherical field, or amethod of trans-coding said spherical field to a randomly chosen audio format. According to the method of encoding the Ambisonics sound field into a spherical field, said sound field is separated, inthe frequency domain, into three components, or optionally two components, and these components are recombined into a total spherical field. According to the method of encoding the spherical field into a stereophonic signal, in the frequency domain, the panning values and phase-difference values are determined, the singularity of the phase difference in the inter-channel domain is determined, thephase correspondence function in the inter-channel domain is determined, and the left-hand and right-hand components of the signal encoded into stereophonic form are calculated. The spherical coordinates are optionally subjected to affine modification such that they correspond to the standard geometric disposition of the left-hand and right-hand channels. The method of decoding into a spherical field is applied to any stereophonic signal, in particular a stereophonic signal obtained by the above encoding method. According to the aforementioned method of decoding into a spherical field, in thefrequency domain, the panning and phase difference are determined, the new position of the phase difference singularity in the inter-channel domain is determined, said position varying temporally, thephase correspondence function in the inter-channel domain is determined, a complex coefficient corresponding to the desired spherical field is determined, and the direction of provenance in the spherical field is determined, said direction being optionally subject to affine modification in order to correspond to the standard geometric disposition of the left-hand and right-hand channels. The method of trans-coding on the basis of a stereophonic signal comprises the above method of decoding to a spherical field, followed by a method ensuring that the spherical field is projected on a specifiedaudio panning law or a binauralisation method.