  In this paper, the coherence between speech and noise signals is used to
obtain a Speech Enhancement (SE) gain function, in combination with a Super
Gaussian Joint Maximum a Posteriori (SGJMAP) single microphone SE gain
function. The proposed SE method can be implemented on a smartphone that works
as an assistive device to hearing aids. Although coherence SE gain function
suppresses the background noise well, it distorts the speech. In contrary, SE
using SGJMAP improves speech quality with additional musical noise, which we
contain by using a post filter. The weighted union of these two gain functions
strikes a balance between noise suppression and speech distortion. A
'weighting' parameter is introduced in the derived gain function to allow the
smartphone user to control the weighting factor based on different background
noise and their comfort level of hearing. Objective and subjective measures of
the proposed method show effective improvement in comparison to standard
techniques considered in this paper for several noisy conditions at signal to
noise ratio levels of -5 dB, 0 dB and 5 dB.
