As explained in your textbook, the credibility of a speaker before he or she starts to speak is called credibility.

Initial

Explanation:

As explained in the textbook, the credibility of a speaker before he or she starts to speak is called "initial" credibility.

"Initial Credibility" refers to the credibility which one has before commencing his or her speech. This type of credibility usually bases on the reputation and credentials of the speaker.

because he had a big bear belly