|Two wires on right (red + black) are for Voltage readings|
Charles was also correct about identifying the GND and +V terminals on the bottom of the electret. After flipping it over, the three little "fingers" were easily visible. I used a Sharpie marker to label them on the outer edge of the component, and I didn't have to solder on any leads as my electret came with two leads already added on.
|Three "fingers" (tiny tracings) on right indicate GND lead|
Before moving on to Experiment 9, be sure to read over the last section of Chapter 8 that talks about a split power supply. Charles' solution is a good one, although you need to understand why he's recommending a very low value of paired resistors if using this method. If you don't understand why splitting the voltage at the 4.5VDC will make it more difficult to obtain accurate voltage readings, read it again... it hit home for me on the second read once I thought about what was actually going to be involved in taking readings of the output voltages.
And here's the Experiment 8 video: