  A control logic has a central role in many echo cancellation systems for
optimizing the performance of adaptive filters while estimating the echo path.
For reliable control, accurate double-talk (DT) and channel change (CC)
detectors are usually incorporated to the echo canceler. This work expands the
usual detection strategy to define a classification problem characterizing four
possible states of the echo canceler operation. The new formulation allow the
use of decision theory to continuously control the transitions among the
different modes of operation. The classification rule reduces to a low cost
statistics for which it is possible to determine the probability of error under
all hypotheses, allowing the classification performance to be accessed
analytically. Monte Carlo simulations using synthetic and real data illustrate
the reliability of the proposed method.
