So I've got this setup:
Positive leads from 2x Piezo spliced together and going to Digital 11.
Negative leads from 2x Piezo spliced together and going to GND.
When I try to use any of the examples for a Piezo the output it EAR SPLITTING. The high notes literally make my ears ring... is there any way to adjust the volume on these?
Thanks!
Put a resistor in series with D11 -try 1k for a start
Allan
Hmm.. I tried putting a resistor of 100k - one end on the Neg side and one end on all 3 positive sides and it didn't have any effect... did I do something wrong?
I think allanhurst meant "a resistor between pin11 and piezo+" (in series, not parallel).
Are you sure they are piezos, not (DC) buzzers.
Leo..
Are they active or passive?
Do the notes change or is it always the same note?
Put tape on the hole if there is one and you want to shush it.
In such a case, you need a current limiting resistor to prevent damage to the Arduino output. Tailor the value to something greater than 220 ohms to suit the volume level you want.
This is what they are
Well, it has "DC" written on it. That should clue you in. It also says, "high decibel", did you overlook that when you ordered it?
No... I just never used a Piezo before and wanted something loud enough to hear... guess I got what I wished for eh? 
Alarm is too alarming . . . . alrighty . . . .
Most people use something like these for active buzzers for Arduino projects
You went and bought alarm buzzers that are supposed to be ear-splitting, so . . . .
Both (post#6 and 9) are NOT piezos, but mechanical buzzers (like the klaxon in your car).
Leo..