Quoting from the same source:
If your using an aural Web browser this Website has left almost everything to be user defined. This is because you should have a voice and reading speed you are comfortable and familiar to.
That's precisely what I'm saying; leave it be and let the user decide.
As for the statement afterwards that you highlighted, most screen readers can very efficiently tell the difference between headers and content if they are marked up as such. To increase and decrease pitch for headers and content to be more distinct is pointless. If you must adjust the aural properties, then do so but may I recommend you leave the content alone as this is the part of the document the most amount of time is spent listening to. I'm sure SR users can forgive a few altered headers.