Open the track you wish to add the phase effect to. Click "File" and select "Open." Then click on the file from the drop-down menu.
Select the portion of audio you want to phase. You can select a whole track by clicking on the sound wave graphic for that track, or you can highlight a specific portion with your cursor.
Click "Effects" and select "Phaser." This brings up a phaser effect interface with a choice of parameters for modification.
Adjust the intensity ratio of the effect. When you apply an effect, there is a "dry" and "wet" signal. The dry signal has no effect and the wet signal does. Between "Dry" and "Wet" is a horizontal slider. The closer the slider is to either "Dry" or "Wet" determines which, if any, of the two signals is loudest. For an intense phase, move the slider right towards the "Wet" side. For a less prominent effect, move it right.
Adjust the "LFO Frequency." An LFO, or low frequency oscillator to use the full name, controls the phase speed and frequency of the phaser. The rate of oscillation determines how much the sound phases and the frequency of the LFO determines which parts of the sound are effected. Move the slider dial to increase the frequency of the LFO.
Adjust the "Depth." The depth of the phaser effect influences how far out of phase. When an old VCR cassette becomes warped, the audio and pictures intermittently slow down and speed up. This creates an audio phasing effect. The rate at which the tape slows or speeds dictates the depth of the phase. The same principal applies to the phase effect. Set it high for a intense, "swooshing" sound. Set it low for a subtle "throbbing" sound.
Adjust the "Feedback." This dictates how strong the phased signal is. If you set it to the maximum, the sound will never stop. It will keep repeating. This is the audio equivalent of putting two mirrors opposite each other. The reflection from one mirror is reflected back to the other and continues to be reflected between each mirror. With the feedback set high, the phase repeats the original sound, then repeats the repeat, then repeats the repeat of the repeat and so on. Set it low for a gentle effect or set it near, but not on, the maxim for a strong phase.
Click "Preview" to hear an audio clip with effect. If you don't like the results, keep tweaking the parameters.