Steady-state performance limitations of full-band acoustic echo cancellers

Due to computational and convergence speed restraints, acoustic echo cancellers used for desktop handsfree units typically use an adaptive filter significantly shorter in length than the length of the enclosure/room impulse response it is attempting to model. A simple measurement based on this impulse response is proposed that gives the maximum obtainable depth of cancellation for a given filter length. By comparing this measurement with actual Echo Return Loss Enhancement measurements for different adaptive filter lengths, the optimum filter length for a given handsfree enclosure and transducers can be determined