Edit Audio Like a Spy

Have you ever watched one of those detective shows on TV, where they’re able to isolate certain sounds in a recording? Or one of those movies where they take a recording and make it sound like the person said something they never said? Unlike many other “enhance that” sequences in movies and TV, these tricks are actually possible.

The following guide demonstrates using Adobe Audition, but many of the principles are the same regardless of the software you use. Just be glad we’re no longer in the days when you had to use a razor blade and blue tape to edit recordings.

The Sound of Silence

We usually ask our voice talent to supply a few seconds of “room noise” at the beginning of a recording. This is standard industry practice, and it’s useful for a couple of reasons. One, you can use it as a pattern to make the background noise much quieter throughout. Two, you can use it to “erase” breath noises in a way that sounds far more natural than any other method.

Drag your cursor to select the quiet part at the beginning of the clip. If you like, you can click the Zoom to Selection button. Audition will zoom in to show you only the portion you’ve selected.

select-noise

Listen to the selection a couple of times and refine it as needed.

To reduce background noise:

  • With your selection still active, go to the Effects menu and select, Noise Reduction/Restoration > Capture Noise Print.
  • Audition will pop up a dialog letting you know it has made a print for you to use in the noise reduction process.
  • Now, select the entire clip: (cmd+A) or (ctrl+A) depending on your operating system.
  • Return to the Effects menu, Noise Reduction/Restoration, and click Noise Reduction (process).
  • Audition will open a dialog showing you how the noise reduction will be applied. The default settings are almost always just right and don’t need to be adjusted. However, as with most of Adobe tools, Audition lets you preview the change and make adjustments before you apply it. Click the Play button near the bottom-left of the pop-up. Click the green Power button to toggle the effect on and off while listening.
  • When you’re satisfied, click Apply.

To replace breaths:

  • Select a large enough sample of background sound. In my work, the longest pause I usually need is about 3/4 of a second, so I like to save at least that much background sound.
  • Copy the selection and save it to a new file. Make sure the settings on the new file are the same as the existing one, including file type, bit rate, and mono or stereo.
  • As you listen to the recording, select breaths and replace them with the background noise. This gives you a much more natural sound than clipping breaths out altogether, or just turning down the volume.
  • Trim the pasted-in background noise to an appropriate duration. I tend to use 3/4 of a second between paragraphs, 1/2 a second between sentences, and 1/4 of a second (or less) in mid-sentence.

Normalizing Volume

Most professional announcers manage their voices to minimize extremes in volume, but not many interviewees have that knack. You can end up with a recording that has very quiet spots that are hard to hear, along with very loud spots that are painful to listen to.

There are all sorts of compressor/limiter tools available, but most of those take some training to use properly. Fortunately, Audition has a tool that can even out the volume of a voice with just a couple of clicks.

  • Select the entire clip, then go to the Effects menu and select Special > Vocal Enhancer.
  • For most voices, male or female, using the settings for Male voice will give you both a richer sound and better volume. Simply click the radio button next to Male.
  • Use the Play button and the Power toggle to preview the change, then click Apply.

Compare the two images below. The image on the left shows peaks that are already near the safe maximum (i.e., any louder and they’ll “clip” or distort). The image on the right shows that the quiet parts have been enhanced without pushing the louder parts over the limit.

The Dreaded Tongue Click

One of the most annoying sounds in narration is the tongue click. If it happens during a breath, it’s not a big deal. You’ll overwrite it with background noise anyway. It’s a different story when that click happens in the middle of a word, though.

The image below is zoomed in on an “n” sound where the narrator made a clicking noise. Notice that most of the waveforms are fairly smooth, while one looks fuzzy or hairy. That’s where the click occurred.

tongue-click-2.png

  • Zoom in on the click and select the jagged bit.
  • Be sure to start and end your selection at matching points in the curve. It’s best to begin and end at points where the wave crosses the zero line.
  • Delete the damaged waveform.
  • Listen to your selection to make sure you’ve got a clean sound, then save your work.

Alternatively, there’s a “brute force” method that sometimes helps if you’re not comfortable performing this kind of micro-surgery. Use this carefully, though, as it can sometimes take out “k” and “t” sounds as well.

  • Go to the Effects menu, and select Noise Reduction/Restoration > Automatic Click Remover….
  • Use the tool’s Preview function to listen to a good long chunk of the clip. Adjust the Threshold and Complexity until you’re sure you’re targeting only the unwanted clicks.
  • Click Apply

There’s so much more about working with audio that we could explore. Things like making voices sound richer or crisper, filtering out specific sounds like hums or whines, fixing the audio track in a video… Let me know in the Comments section if you want to see another post on this topic, or if you have any specific questions.

(by Rissa Karpoff)

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s