Tip #1 - Some Garage Band enhancements to "dry" voice.
Sample of poorly recorded audio, enhanced with Levelator.
Take a look at the two clips below. Which do you think is louder?
The one on the right has higher peaks, so you might think it's louder. In fact, the one on the left is much louder. The sample on the right is human voice. The one on the left is heavy-metal music.
The outline of a waveform indicates its voltage. It's what you'd see on an oscilloscope, for example. But the perceived loudness more closely corresponds with the power of the signal, and that is represented by the area under the curve -- the area between the waveform outline and the horizontal axis. At the zoom level of this example, loudness roughly correlates with the density of the blue color. The greater density of the signal on the left suggests that it will be loude