"More extemporaneously" can be replaced by a variety of synonyms depending on the context. If someone is speaking without prior preparation or notes, they may be described as speaking impromptu or improvising. They could also be described as speaking off-the-cuff or ad-libbing. If they are speaking in a natural and unrehearsed manner, they may be called spontaneous. Alternatively, if someone is speaking informally, casually, or in an unscripted manner, they may be called colloquial or conversational. Finally, if someone is speaking with passion or enthusiasm, they could be described as speaking passionately or fervently. Choosing the right synonym is important when trying to convey the exact meaning of a sentence.