Tutorial: Fixing Flawed Audio in Adobe Creative Cloud

Beefing Up the Audio With Compression

The final problems were the faintness of the vocals and low overall volume, which I’ll address with audio compression and gain. Note that if vocal volume is low but the vocals are otherwise OK, you wouldn’t use compression, since that changes the tone of the vocals. Rather, you would normalize or otherwise adjust gain without compression.

What is audio compression? Essentially, it reduces the volume of louder regions in a waveform to make the volume more uniform and the vocals more distinct. Think back to a car sales ad on the radio or TV with an impossibly deep voice, that’s likely audio compression at work, obviously to a much stronger degree than I want to apply here.

To apply compression, select the entire waveform and choose Effects > Amplitude and Compression > Multiband Compressor (Figure 6, below). I typically use the Raise Vocals preset and leave most of the sliders and other options as they are. Then, because compression drops the volume of some portions of the audio file, and because the volume was a bit low anyway, you have to adjust gain upward via the Output Gain slider on the right. To find the right value, I start previewing within Audition, and boost volume until the audio meter on the bottom shows I’m in the desired range, which for me is between -3 dB and 0 dB. On the bottom left of the effect dialog, you can toggle the effect on and off to hear the difference. The first few times I applied this effect I definitely overcooked the audio, producing an overly harsh vocal track reminiscent of the aforementioned car advertisements. So, be careful.

Figure 6. Boosting clarity and volume with audio compression

When you’re done, click Apply to apply the effect. Examine the waveform in Audition to make sure the volume is acceptable. Too much gain will produce flat regions on the top and bottom of the waveform, which is called clipping, and can distort the audio. If you see that, undo and apply the effect again with less gain. If the volume is still too low, you can Normalize or otherwise adjust gain as you normally would.

Figure 7 (below) looks good to me; if you compare this waveform with the starting point to the right in Figure 3, you’ll see that we reduced, but didn’t eliminate, the bushiness around the centerline while boosting overall volume. The result is an audio file that is more clear and sounds more professional.

Figure 7. A clearer, louder, and easier-to-comprehend vocal track.

Note that you can apply the Multiband Compressor effect in Premiere Pro with full access to all controls. I still prefer Audition, if only because the waveform display is more informative, but you can get it done in Premiere Pro.