About the "s" or "z" sound, I really have no clue

when to use them. But it seems that when the "s" is used in a word that is a verb, it takes on the sound of "z" and the sound "s" when it is used in a word that is a noun or adjective. For example, words like "use", "close", and "advertise" follow this rule. However, it is dangerous to generalize because there are always exceptions, like the "s" in "phase". Maybe some experts could help us out on this.

I have only recently began to pay attention to such subtleties. Listening to your recording also helps me. What I usually do is first listening to the recording without reading the text. If there is something I don't get, I will look it up. The "something" may be a new word or a word mispronounced. So...

Just my 2 cents.