Sound Advice: Audio Mixing: The Perfect Blend

Coffee gourmands know: You have to find the right blend of beans to make the perfect cup of coffee. Mixing audio requires similar skills. Today’s technology offers all the bells and whistles you could ever want, but it takes a discerning ear to create a smooth audio mix. While you may not have golden ears, you can learn some fundamental mixing skills that will improve the audio on your next video project. Even Juan Valdez himself would be proud.

The Right Beans

In this case, that means starting your production with the very best raw materials. Computer folks always say "garbage in, garbage out" and the same applies to your video. It’s impossible to eliminate all the background noise from your field recordings, so make sure you have clean, clear audio in the first place. Spend a little extra time fine-tuning your microphone selection and placement and don’t forget to monitor the recording with headphones. When recording voiceovers, use the best microphone you can get your hands on, record in a quiet location and find the cleanest signal path to the recorder. With background music, locate the highest quality version of the cut you want to use (this means avoiding compressed distribution formats such as MP3s, WMAs and RM files like the plague). All of these variables combine to improve your audio quality even before the edit session begins. Once you start editing, you’ll spend less time trying to fix things and your mix will sound complete sooner than you expect.

Into The Grinder

You’ve got great material, now you’re ready to edit. Depending on your video software, you may have several options available. For example, Adobe Premiere includes some audio-specific tools to shape the sound in your video. First is the audio mixer view. This window looks much like a traditional audio mixer, complete with volume sliders and virtual pan knobs along with track mute and solo buttons. This interface is great for general audio adjustments and offers a quick way to get your mix happening. Alternatively, you can use the on-track volume and pan adjustments (called rubber bands) for fine control and complete automation of your changes. Premiere also includes a number of audio-enhancing tools such as equalizers, dynamics controls, reverb and echo effects – many of the same items you would see in a recording studio.

Regardless of your editing software, the trick in mixing audio is to keep things flowing smoothly. Volume levels between independent clips should sound similar even with different subjects. Background music never covers the dialog and should move in and out of the mix as required. A possible exception to these rules applies to sound effects. Many times sound effects are included to grab our attention and an appropriate volume difference helps accomplish this. Use all the tools at your disposal to achieve a smooth and balance mix, but apply them sparingly. It’s just as easy to ruin your soundtrack with too much processing.

Listen To Your Elders

One of the best ways to learn what makes a good audio mix is to listen to professional productions. Depending on the type of video you’re producing, find a similar project and use it as a reference. The best part is that you can find virtually any type of production style, 24 hours a day on TV. Surf through your satellite or cable channels until you find something with content that resembles your project. Your public library likely has a cache of how-to videos and documentaries to stir the creative juices. When you find the right source, compare what they’ve done with their audio to what you have in mind for your production. Pay close attention to the clarity of voices and their relationship to any background music. What type of music (if any) did they use to support the topic of their video? Did they use sound effects or special audio processing? You certainly don’t have to copy their production values verbatim, but it’s fun to dissect another project and select certain elements to emulate in your work.

One Cream, Two Sugars

To put the final shine on your audio, consider using a trick from the recording studio world – mastering. Continuing our coffee analogy, think of mastering as the cream and sugar that makes the coffee just the way you like it. Mastering takes your finished soundtrack and further refines it with dynamic range control and equalization. The process works like this. In your video editing software, export the audio-only portion of the project (make sure to use the correct sampling rate – 44,100Hz for CD audio, 48,000Hz for DV projects). Then, in an audio editor like Sound Forge or Cool Edit, apply some equalization and dynamics processing to even things out. Selective tone control can smooth out that booming male voice or tame the sizzling highs in the music track. Dynamics control (compression and limiting) will reduce the difference between the loudest and softest portions of your project, making it easier to understand on a broad range of playback systems. When you’re finished, save the file and import it into your video project, then mute audio playback on all the old tracks. Although you can do much of this within your video editing software (depending on the quality of its audio tools), mastering takes a good soundtrack and makes it even better.

Wake Up Call

You’ve spent hours or even days making small adjustments to your mix and it sounds great – at least on your editing system. Unfortunately, most folks won’t hear your project on that system. You need a reality check.

Make a VHS copy of your video and play it on another system, preferably away from your computer in a living room, bedroom or home theater. Ironically, the best reality check system is also the worst sounding. Play your video in mono through a dinky TV speaker. If it sounds good under these circumstances it will probably sound great on any system. In addition, you’ll pick out things that don’t work with your mix. It may be something as simple as a balance problem or as serious as vanishing voices. Whatever you find, take notes and repair the problems back in the edit suite, then repeat the process.

After Dinner Cappuccino

Like most good things in life, audio excellence requires more planning and work, but the results are always worthwhile. The level of technology at hand on our desktops rivals the major studios. Even some feature films are shot on DV and edited with the same tools available to you and me.

The line between the consumer and the professional has blurred, with the only difference being the skill of those using the tools. Learn to use the tools you have and you’ll be producing quality audio (or decaf mocha frappe) in no time.

[Sidebar: Music Too]
If you produce your own music with MIDI or loop-based software like ACID, find popular recordings of similar styles and use them as a reference. What is it about these songs that hold your interest? Listen closely to the synchronization between the bass guitar and drum elements as well as their balance in the mix. Examine how the mixing engineer uses volume and left-right placement to make room for all the instruments. With some practice, you can use the same techniques to produce a killer music track. Practice makes perfect.

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