I listened to the 3 samples, and I must say some of it is quite close and some of it is completely wrong with how I would expect that person to sound saying those words.

Like the first one "just his scribbles that charmed me" sounds so weird compared to how the sample sounds.

Second one, sounds very close but again "just his scribbles that charmed me" sounds off and wrong. His "scrouples? that charmed me".

Third one as well, it's very up and down (not sure the correct science words for that type of speaking), "Dynamo and lamp.... Edison realized". The second one is completely flat and seems computer generated.

Overall these don't seem very good to me at least. It's clearly not to the level of some other AI coming out where it is very difficult to determine the human part, I could easily pick up the human and generated version from these samples.