  STOI-optimal masking has been previously proposed and developed for
single-channel speech enhancement. In this paper, we consider the extension to
the task of binaural speech enhancement in which spatial information is known
to be important to speech understanding and therefore should be preserved by
the enhancement processing. Masks are estimated for each of the binaural
channels individually and a `better-ear listening' mask is computed by choosing
the maximum of the two masks. The estimated mask is used to supply probability
information about the speech presence in each time-frequency bin to an
Optimally-modified Log Spectral Amplitude (OM-LSA) enhancer. We show that using
the proposed method for binaural signals with a directional noise not only
improves the SNR of the noisy signal but also preserves the binaural cues and
intelligibility.
