Abstract: The invention relates to an adaptive filter unit, in particular for being used as an echo canceller, comprising a first filter input, configured to receive a first electric audio signal, indicative of a first audio signal A(t), a second filter input, configured to receive a second electric audio signal, indicative of a second audio signal B(t), a processor and a filter output. The processor is configured to calculate and provide audio estimation data X(fn, A(t1, . . .

Abstract: The invention concerns a communication device for placement at the ear of a user. A battery and transmission part is shaped to rest behind and above the ear lobe of a user and a speaker and microphone part is arranged to extend downwards in front of the ear canal. The two parts are interlinked to pivot, at least in the sagittal plane, with respect to each other and the battery and transmission part accommodates a battery as well as signal processing and transmission electronics, and the speaker and microphone part accommodates a speaker element and a microphone boom arm and further, the two parts have mating surfaces such that a pivotal motion between the two, when the device is not at the ear, will bring a surface of the first part and a surface of the second part together. Further the link between the two parts comprises a hollow ball joint connection allowing leads to pass through the ball joint.