I’m not an audio expert but I think the sounds are much better than the old ones which cause dizzy if I listen for too long. Maybe a little bit better than the natural voices of MS Edge brwoser but I’m not sure about this.
In the past, I used to attempt to use an extension called “Chinese words separator” to show pinyin and listen to their natural voices but it was not successful because it didn’t display the pinyin nicely. The new neutral voices and ruby reading in Pleco 4.0 is a real winner for me.
By the way, the pinyin reading in “Chinese words separator” extention has one interesting feature is that it italicizes the words that have 2 different pronunciation; italicizes and underlines the words that have 3 pronunciation; italicizes and double underlines the words that have 4+ pronunciation.