Equalization is where you change the "tone"... the 'treble' and 'bass' knobs on amplifiers are a simple form of eqaulizers. I am sure audacity has some sort of equalization setting. You would want to aim toward increasing the mid-range frequencies where the voice register is at, and lower the bass and higher treble frequencies to reduce noise. Compression is where you decrease the sound between low volumes and high volumes.... you would increase the overall volume by compressing and increasing the volume... this can be, however, somewhat destructive to the audio, so you would take special care when making changes (so always keep your original file that was not messed with). "Normalization" is when the recording is analyzed by the computer to find the loudest spike in volume ("peak"), and it raises the entire volume of the recording to where the peak is at the loudest possible volume before distortion. It may not be necessary though, if you raised the overall volume during compression.