A method and apparatus to extract an important frequency component of an audio signal and a method and apparatus to encode andor decode an audio signal by using the same. A second capacitor circuit coupled to ground balances the first capacitor circuit. The first UMA device is connected to the local area network and the UNC is connected to the external network. 25 inches disk drive cover plate, or to the 3. The invention also relates to an assembly comprising a second module for a vaginal speculum and two or more first modules for a vaginal speculum, the two or more first modules comprising at least two first modules with mutually differing dimensions. The control detects the temporal interval of the two last-received impulses and activates the electric motor such that the fluid quantity to be delivered, taking the previously evaluated interval as a basis, is distributed over the subsequent impulse interval.