Double-click the Soundbooth desktop icon.
Click on "File" and select "Open." When prompted, select "New Session." This opens a blank session in the Soundbooth interface.
Click on "Import File" tab. Select the appropriate file from your browser.
Drag the file into the Soundbooth timeline.
Click "Effects" and select "EQ: Graphic." This opens a graphic equalizer window. A graphic equalizer permits you to boost and diminish specific frequencies. Typically, equalization is used for tweaking the sound of audio. However, you can use it to mute unwanted sounds, using frequency as a selection parameter.
Select "Play" to hear your adjustments in real-time.
Click on "Settings." This opens up a new window with four slider dials. They are labelled, from left to right, "Low," "Low-Mid," "High-Mid" and "High." Each dial governs a wide frequency range.
Slide the "High-Mid" dial down to zero. This cuts the frequency band upon which typical vocals exist. It does not cut all vocals, but it takes out a decent chunk. The downside is that this approach may take out some other sounds, too.
Click on "Effects" again and select "EQ:Parametric." This tool lets you filter out specific frequencies.
Slide the dials governing the frequencies between 200Hz and 3Khz to zero. This is the typical range upon which vocals exist.
Hit "Preview" to hear the sound of the audio without these frequencies. While it may have removed all of the vocals, there may be some "collateral damage" affecting guitars, brass and some strings which occupy a similar frequency range. If the arrangement is quite bare, this approach may work. For fuller and more lush recordings, a more defined approach is required.
Click on the curve. The curve, which is superimposed on a grid, represents the frequency range in the currently selected audio. The vertical grid axis represents amplitude and the horizontal axis represents frequency.
Move the curve around with your cursor. As the curve moves around the grid, different frequencies become highlighted. When you the vocals become most prominent, stop moving the curve. The last selected frequency remains highlighted.
Click on "Gain" and drag it zero. Gain governs the amplitude of the selected frequency. This effectively cuts the frequency band upon which the vocals exist. Because vocals exist over multiple frequency bands, repeat this process until the vocals have effectively been "distilled" from the audio.