Magnitude squared coherence for a unichannel pure tone
O. D. Grace · The Journal of the Acoustical Society of America · 1980
The probability density function of the magnitude squared coherence estimator is determined for the case of a pure tone in one channel and Gaussian noise in the other channel. It is found to be the same probability density function as for the case of Gaussian noise in both channels. It follows that the detection thresholds for both cases are the same and that no ad hoc threshold adjustment is required.