The phrase "credible speech" is correct and usable in written English.
It can be used when discussing the reliability or trustworthiness of a speech or presentation.
Example: "The politician's credible speech convinced many voters to support her campaign."
Alternatives: "trustworthy address" or "reliable presentation."
Even at the Democratic convention, where it was generally agreed that Mr. Gore delivered a credible acceptance speech, the strongest case for continuing the policies of the Clinton administration was made by the president.
Having turned down the volume and the heat — the elements that energize his core constituency — he revealed himself incapable, at least for the moment, of giving a credible political speech.
With its position at the center of the concentric rings of soldiers' graves and the continuing endorsement of Lincoln's native state the Soldiers National Monumentt persists as a credible location for the speech.
In addition, Markham et al. [ 11] reported credible evidence that children with speech and/or language difficulties can provide insight into their own HRQOL, and that common themes found in these discussions closely reflected domains of generic HRQOL measures [ 11].
His speech is made credible by a weird self-righteousness that the child records but cannot discern.
Which was why, for this year, at least, Mr. Booker's speech had the credible sound of someone who had walked through fire and survived.
I watched the speech and found it credible and constructive.
Statistical approaches, such as hidden Markov model-based speech synthesis, allow a credible voice to be generated from less recorded speech.
Mendes makes a more credible vamp, and Crystal gets one short speech, during a contretemps with Mary, that puts the whole film into perspective.
Research in social psychology indicates that speaking differently from the dominant group results in individuals being judged as less credible or knowledgeable, regardless of the content of their speech (Lev-Ari and Keysar, 2010).
