The evolving field of headphones, particularly hearables, and current developments in low power audio processing chips raise the interest in active approaches to address the problem of ambient noise. Methods of Active Noise Can- cellation (ANC) are well suited as a supplement for passive attenuation, as they work specifically well for low frequen- cies. They are offering more flexibility to account for chang- ing acoustic conditions and requirements. This contribution gives an overview of the ANC headphone problem and addresses the specific algorithm design challenges.