This paper will focus on several types of adaptive filters that can be applied to the problem of audio echo cancellation. The widely used LMS will be briefly discussed. However, there are other variants of the LMS that are better suited to implementation in embedded DSP systems. For example, we will examine the BLMS (or Block LMS) and a frequency domain variant called ‘FBLMS’. Fundamentally, all three of these adaptive filtering techniques are mathematically quite similar. However, they have substantial differences in terms of their implementation and hence their utility in embedded DSP systems.