This paper presents a method of audio signal separation from stereo mixtures using binary masking in time-frequency (TF) domain based on the spatial location of the audio sources. The TF representation of audio signal is obtained by Hubert spectrum (HS). The Hubert transformation together with empirical mode decomposition (EMD) produces HS which is a fine-resolution TF representation of any nonlinear and non-stationary signal. The sources are localized in the space of time and intensity differences between two microphones' signals. The separation is performed by masking the target signal in TF domain considering that the sources are disjoint orthogonal. The experimental results of the proposed method show a noticeable improvement of separation efficiency