--Hören Sie Radio? - Nein, ich höre nicht Radio. Besser: "Nein, ich höre kein Radio."

I personally suggest that you may refer to some answers given in the other posed question, http://www.italki.com/answers/question/59694.htm In terms of negation in German, the general rules are governed as, 1) For negation of a noun in general, "kein" is used (with proper declension and gender accordance). 2) For negation of the others, such as a verb, an adjective or an adverb, "nicht" is used (without any necessary declension or accordance). Referring to your examples, if the principle negation matter is "hören" (which is a verb), then in a simple-verb sentence, "nicht" should be placed at the end, that is, -- Hören Sie das Radio? -- Nein, ich höre das Radio nicht. If the principle negation matter is "das Radio" (which is a noun), then we tend to use "kein" for negation, and the sentence should be like the one given by respondent domasla, that is, -- Hören Sie das Radio? -- Nein, ich höre kein Radio. If, however, the speaker has an intention to emphasize that he/she is not listening to the radio, but something else, like the music, then the respective structure in German is given as "nicht ... sondern ...": -- Hören Sie das Radio? -- Nein, ich höre nicht das Radio, sondern die Musik. I hope that my answer may help you be somehow clarified of some concern in the concept of negation. Good day. / Schönen Tag.