Is listening and believing to the speech delivered by an ullammah without verifying the truth from the Quran considered as shirk? Believing and accepting directly what the Ullammah is explaining.
An ullama has an informed opinion about Islam: while their views are fallible, they're most likely correct. Moreover, when they're incorrect, their errors are more likely to be minor.
It's over-the-top to consider this as shirk---they're not being treated as anything remotely comparable to a god, just a reliable source of information.
In fact, even the Prophet Muhammad was limited in making rulings:
... whatever I decide for anyone which by right belongs to his brother, he must not take anything, for I am granting him only a portion of Hell.
Sunan Abi Dawud 3583 [grade: sahih]
Conforming to the teachings of another is called taqleed, and its history is discussed in The Evolution of Fiqh by Bilal Philips (pdf). It's generally described negatively by the formative Sunni Imams (Philips even writes "Imaam ash-Shawkaanee took the position that Taqleed was Haraam ...").
So it's good to verify sources if you can, but if you're not in a position to do so, it's safest to follow a knowledgeable opinion.