If your digital music collection contains songs recorded or mastered at different volume levels, listening to music on your computer can involve constantly adjusting the volume control. You can use Audacity to make all the songs in your collection play back at the same volume. The process of equalizing volume levels is known as normalization; Audacity includes a built-in "Normalize" effect you can apply to all the songs in your music library.
Launch Audacity. Open the "File" menu and select "Import." Click "Audio" to open a file browser window.
Navigate to the directory containing the songs you want to make the same volume. Press and hold the "Ctrl" key, then click each of the songs. Click the "Open" button once you've selected all the songs you desire.
Press "Ctrl+A" simultaneously to select all the songs once you've imported them.
Click "Effect" and select "Normalize" from the drop-down menu. Audacity opens the Normalize dialog box.
Click to check the box next to "Normalize maximum amplitude to." Type the desired volume level into the "dB" text box.
Click "OK" and wait while Audacity makes all your songs the same volume.
Click "File," then "Export Multiple." Click the "Choose" button, select a location for the songs and click "OK." Click "Export" to save the songs.