An improved base station which cancels the effects of known fixed interference sources produces a signal substantially free from the interference sources thereby increasing total channel capacity. In the audio apparatus, an amplifier device drives the loudspeaker with a driving voltage. The opinion data includes one or more features discussed in the opinion documents, one or more key phrases included in each feature, one or more text snippets included in each feature, and at least one sentiment expressed in each text snippet. If the listener reacts to an item of the default playlist in a prescribed manner, the listener is automatically switched to a sidechannel where the alternate playlist is immediately started. A second part is attached to the exterior of the thermoelectric element and coolant flows therein.