An angle-dependent operating device and method for obtaining a pseudo-stereophonic audio signals, such as through the parameterization of a fictitious opening angle α+β, where α is the fictitious left-hand opening angle (situated to the left of the main axis of the monophonic audio signal to be stereophonized), and β is the fictitious right-hand opening angle (situated to the right of the main axis of the monophonic audio signal to be stereophonized), where it may be that α≠β. This is provided for the situation of fictitious opening angles α+α which are asymmetric with respect to the principal axis of the monophonic audio signal to be stereophonized.