Audacity is a digital audio recording and editing freeware application for Windows, Mac OS X and Linux operating systems. While not a fully featured audio editing application, Audacity is a competent program that features plug-in support and a selection of post-production tools. Mastering is a post-production process that involves applying various effects to the final mix of a recording in order to create a master file. The Normalize and Equalization effects within Audacity enable you to master preexisting vocal tracks and other audio files.
Click "File" on the main Audacity tool bar and select "Open." Browse to the location of the vocal track that you want to master. Highlight the file and click the "Open" button.
Click "Edit" in the main tool bar and highlight "Select." Click on the "All" option from within the Select drop-down menu.
Click "Effect" in the main tool bar and select "Normalize." Enter a value of "0.0" into the dB field, and make sure that both check boxes are ticked. Click the "OK" button to normalize the audio.
Click "Effect" in the main tool bar and select "Equalization." Click the "Select Curve" drop-down menu to expand the selection of equalization curves. Select the desired equalization curve from the list by clicking on it. Press the "Preview" button to hear a sample of your audio with the applied equalization curve.
Click within the Equalization Grid to add new points to the curve. Click and drag the curve to reposition it within the grid. Press the "Preview" button to hear a sample of your audio with the altered equalization curve. Continue manipulating the curve until you are satisfied with the result.
Click the "OK" button within the Equalizer menu to apply the equalization curve to the audio file.
Click "File" in the main tool bar and select "Export." Select the desired audio format from the "Save As Type" drop-down box and click the "Save" button to export the mastered audio file.
Multiple equalization curves can be applied to a single audio file. After applying an equalization curve, select "Equalization" from the Effects menu to apply another curve.