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Cleaning and restoring audio

Garrick Chow

One of the most common, and the most annoying, issues facing anyone working with audio is the existence of unwanted noises and sounds in audio clips. You may have a great audio clip, but it can be filled with background noises: cell phones ringing, chairs squeaking, or someone coughing. It may even be a constant noise, such as a hiss from a microphone. In this tutorial, you’ll learn some ways to use Adobe Soundbooth CS3 to remove and reduce noise in audio clips.

Requirements

To follow along with this article, you will need the following software and files:

Watch this tutorial in the Adobe Creative Suite 3 Video Workshop.

Cleaning up audio

  1. Choose File > Open and open Interview.wav.
  2. Press the Play button <<icon>> to listen to the audio clip. The clip has a few problems. Notice that a cell phone starts ringing around the 2-second mark and a hiss in the background is present throughout the entire clip. Click the Stop button <<icon>> when you are finished.

Figure 1
Figure 1: Press the Play button in the Editor panel to listen to the audio clip.

  1. To remove the hiss, first you need to find an area in the clip that contains only the noise you want to remove. Start looking around the 7-second mark. Zoom in on the clip by clicking the + (plus) key. Notice that a flat area is in the waveform starting at 00:00:06.75. Drag your mouse over this flat area to select the range and then click the Play button. Click Stop when you finish listening.

Figure 2
Figure 2: Find a place in the waveform where the sound you want to remove is isolated, and select the range.

  1. Choose the Tasks panel. Click Clean Up Audio.

Figure 3
Figure 3: Choose Clean Up Audio from the Tasks panel.

  1. Clean Up Audio contains tools to clean up noise as well as other flaws, such as clicks and pops. Clicks and pops are generally short, intermittent sounds, while noises are constant background noises like the hiss you heard in the Interview.wav clip. With the sample range selected, click Capture Noise Print.
  2. Capture Noise Print analyzes the selected range’s noise frequencies and determines what frequencies to remove from the entire clip. To actually remove the noise, click the Noise button <<icon>>.
  3. The Reduction slider lets you determine how aggressive Soundbooth should be in determining what is and isn’t noise in the file. Because you have such a good sample, move the Reduction slider up to 75%.

Figure 4
Figure 4: Use the Reduction and Reduce By sliders in the Noise dialog box to determine how far to reduce noise when it is detected.

  1. Make sure Use Captured Noise Print is selected so that Soundbooth uses the selected range as a sample and doesn’t treat it as the entire clip.
  2. The Reduce By slider indicates how much to reduce the volume of the noise that it finds. To find out where exactly to set this slider, it’s best to use your hearing.
  3. If the Power button <<icon>> is not green, click it to turn it on. The Power button allows you to hear a live preview of the changes the sliders make when you click Preview.
  4. Click Preview to play back the adjusted clip. While the clip is playing you can continue to adjust the sliders and get live feedback.
  5. When you’re adjusting the clip, make sure that you are removing the hiss without distorting the speaker’s voice. Click the Stop button when you are finished previewing the clip and adjusting the sliders.
  6. Click OK to commit your changes. The Removing Noise dialog box appears while Soundbooth applies the noise reduction to the clip. Watch the selected range to see how the change affects the hiss.

Figure 5
Figure 5: The Removing Noise dialog box appears while Soundbooth removes the noise from the clip.

Removing a Sound

Now you’ll remove the ringing from earlier in the clip. In most audio-editing applications, removing a sound that occupies the same time space as audio that you want to keep can be difficult to impossible. It’s hard to tell from just looking at the waveform where the ringing occurs. Soundbooth, on the other hand, makes this task much easier with the spectral display.

  1. Find the effected portion (between 1 and 4 seconds) and click and drag to select the range.
  2. Choose the Tasks panel and click Remove A Sound. This opens the spectral frequency display of the waveform, which shows the audio clip in terms of frequencies based on color. To show or hide the spectral display at any point, choose View > Spectral Frequency Display.

Figure 6
Figure 6: The spectral display appears when you select Remove A Sound from the Tasks panel.

  1. Click the Play button again to see which color and pattern best represent the cell phone ringing. Notice that the sound corresponds to the two dotted lines running through the middle of the selected range.
  2. To select the dotted lines, choose the Marquee tool <<icon>> from the Tools panel, and click and drag a rectangle around the lines in the waveform at the top of the screen (the left channel; the selection is duplicated in the right channel below). Like Photoshop and other Adobe programs, Soundbooth is a visual editor and allows you to sample any portion of an audio clip based on what you see, without having to sift through what you hear.

Figure 7
Figure 7: Draw a marquee around the sound of the cell phone ringing to select it.

  1. Choose the Tasks panel, click the Marquee tool in the Tools area, and select Play Selected Frequencies Only to play only the selection captured in the marquee. Click the Play button to make sure you captured the cell phone ringing.

Figure 8
Figure 8: Choose the Marquee tool and select Play Selected Frequencies Only in the Tasks panel so that Soundbooth knows which portion of the clip to remove.

  1. Click Stop and adjust your selection as needed.
  2. Position your mouse over the selected area. When the Amplitude slider appears, click and drag the number all the way to the left (to -96 DB).

Figure 9
Figure 9: Click and drag the volume all the way to the left to lower the volume of the selected sound: the cell phone ring.

  1. Uncheck Play Selected Frequencies Only and click Play to play the clip again. The cell phone ring is gone from the clip. With just a few mouse clicks, Soundbooth allows you to find, isolate, and remove a noise from your audio clip.

Where to go from here

For more information and additional tutorials, visit the Adobe Design Center.