Research done by many people including Dr. Abigail Manynard at the UCONN Agricultural Research Station in New Haven, Conn has shown that there is no significant change in soil pH after years of adding oak leaves or pine needles to that soil.
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The best would be to grow blueberries in a medium with 60% to 70% sphagnum peat moss and the remainder a good quality compost.
The mulch will be of benefit to your plants but added nitrogen may be required to compensate for what is being used to decompose the mulch.
To change the pH otherwise would mean the application of elemental sulphur to the soil or growing medium. You would have to determine how much can be safely added on an annual basis. What is the soil pH now?
An agricultural representative once mentioned that after 20 years or so of the application of a sulphur fertilizer, a farmer reduced the pH of a field by 1 unit - an astounding amount. Most prairie soils in the area are 8.0 to 8.5.