  This paper considers speech enhancement of signals picked up in one noisy
environment which must be presented to a listener in another noisy environment.
Recently, it has been shown that an optimal solution to this problem requires
the consideration of the noise sources in both environments jointly. However,
the existing optimal mutual information based method requires a complicated
system model that includes natural speech variations, and relies on
approximations and assumptions of the underlying signal distributions. In this
paper, we propose to use a simpler signal model and optimize speech
intelligibility based on the Approximated Speech Intelligibility Index (ASII).
We derive a closed-form solution to the joint far- and near-end speech
enhancement problem that is independent of the marginal distribution of signal
coefficients, and that achieves similar performance to existing work. In
addition, we do not need to model or optimize for natural speech variations.
