Audio Advice: Traveling Sounds

You know the game: name five things you would take if stranded on a desert island. Now, before you name a cell phone, matches, and a case of your favorite beverage, let’s twist the game a bit and decide on five audio tools that no video editor can be without, whether you’re stranded on a desert island or a Dallas airport. The premise may sound a bit silly, but think about it. You won’t always edit in your nice, cushy edit suite. In fact, one day you may find yourself frantically slashing video on an airplane or in the back seat of a car. You won’t have all your fancy plug-ins or decent speakers to monitor your audio with. Should you find yourself in such a situation, you’ll be glad you mastered these five essential tools.

Normalization

Probably the most important audio tool in your kit, normalizing analyzes the audio in a video clip and boosts the volume so the peaks are at maximum volume. This indispensable process ensures all your audio clips will play back at their full potential. Every video platform is different, but the procedure usually involves selecting the clip, and then choosing the Normalize option. Unless your original audio was pretty loud during recording, the Normalize process will apply some boost — sometimes quite a bit — resulting in a nice, loud clip that can compete with other audio elements in your project. Tip: when normalizing interview audio, import longer clips and apply normalization to the entire clip before slicing it into smaller chunks. Since the normalization will stay with each edit, you can do it once instead of dozens of times. Regardless of the audio you’re normalizing, you may have to manually tweak the settings to get things just right.

Filtering

Your car uses several filters to keep bad things out of the engine. Your audio can benefit from some filtering too. Audio filters allow certain parts of the sound spectrum to pass while removing other parts. Your very best filter friend is the high-pass filter. Applying a high-pass filter to your recorded audio removes the low-frequency elements — like wind and handling noise — and lets the upper portion through unaffected. A low-pass filter removes the higher frequencies while a band pass filter removes some of the upper and lower audio, resulting in a narrow audio spectrum. Applying a filter is usually a drag-and-drop affair, selecting the filter from a list and dragging it onto the appropriate audio clip. Afterward, you’ll have to make some adjustments to the filter since the default settings rarely work for utility use. Filter setup involves adjusting the cutoff frequency for your intended use. For example, a high-pass filter on your dialog track might have a cutoff frequency of 100Hz. This ensures a minimum of
low frequency nasties will make it into your video.


Equalization

Equalization or EQ is similar to filtering, but with much more control. Think of equalization as the tone control on your car stereo taken to a much grander scale. Equalization of your audio soundtrack requires more than the simple twist of a knob, but the results are worth the effort. A simple equalizer has one band of control for each octave of the sound spectrum, giving you control of nine or ten ranges of sound. A more aggressive EQ might have as many as 31 bands of control — three for each octave. You can boost or cut each band to shape the tone of your audio. To improve the clarity of your dialog, you may have to boost the upper two or three bands. This increases the high frequency content of the sound, making it crisper and easier to understand. Alternatively, you could reduce the sound in the middle or lower bands to remove the mud in that range, also improving the clarity of sound. However you choose to apply EQ, start with small adjustments and try pulling a few bands down before you start boosting everything else.

Dynamics Control

Dynamics are the differences between the loudest and softest part of your audio. A gunshot, for example, has a huge dynamic range, since it goes from silence to deafening in a split second. At the other end of the scale, a typical pop song has a very small dynamic range so it will sound louder on the radio. There are two types of dynamic range control filters — limiters and compressors. A limiter allows you to set a ceiling on the sound and will keep any and all sound from exceeding that setting. Limiters are great for controlling sounds with wide dynamic ranges. A compressor, by contrast, lessens the difference between loud and soft, bringing the loud sounds down in volume and boosting the softer sounds. Compressors are perfect for controlling sounds that change volume over time, like dialog and music. You can also use your dynamics plug-ins to boost the overall volume of your soundtrack, just like that song on the radio.

Audio Position

The previous four audio tools deal with the volume and tone of your audio, but what about its location? Panning is the process of placing your sound at a specific spot in the sound field. For stereo projects, this means locating sounds in the left or right speaker. For surround mixes, you can put your sounds virtually anywhere in the room. On a mixing console, there is a pan knob and a simple twist will place sound anywhere between the left and right channels. In your editing software, audio panning may be just as simple, or as complicated as setting key frames and drawing pan envelopes. Regardless of how your software handles it, this is a valuable tool. While most dialog is anchored in the center, clever panning can put sound effects and music across the screen or even out of the frame.

While it’s unlikely you’ll ever be stranded on a desert island with video to edit, it’s still a good idea to get familiar with the essential audio treatment tools. Your videos will have more punch, be clearer and just sound better overall. Your clients will be happier, your reputation as a producer will grow and nobody will be able to vote you off the island.

Contributing Editor Hal Robertson is a digital media producer and technology consultant.


Sidebar: Reality Check

If you really are editing video in the wild, one of the first casualties will be your audio monitoring. Sure, you can monitor with headphones, and that will give you a good idea of the basic blend and quality of sound. Unfortunately, headphones don’t sound like speakers and most of your viewers will hear the finished product on speakers. If you can catch a transport off the island, take your edited video along for a test on several playback systems. Try everything from a home theater to a simple mono television. If the mix holds up here, great. If not, make notes about where it was hard to hear dialog, where music was too loud or soft and how the sound effects fit in the mix. Once you’re back in your desert paradise, make adjustments based on these notes. Your newly balanced soundtrack should playback nicely on virtually every system. If anyone ever gets to see it, that is.

Sidebar: Post-Processing in an Audio Editor

For whatever reason, it may be difficult or impractical to edit audio in your video software. If that’s the case, it’s easy to edit audio in a dedicated package like Adobe’s Audition or Sony’s Sound Forge. You can export audio from individual clips or your entire project, treat it as needed in the audio app and then drop it back into your video project. In an audio-specific program, adjustments are easier with a greater degree of control and you’ll have every bell and whistle known to the free world at your disposal.

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