Noise Reduction

Some audio files contain unwanted noise, making it difficult to hear the voices, music, or other content of the file. Soundtrack Pro features two commands, Set Noise Print and Reduce Noise, that you can use together to reduce noise in an audio file or selection.

Set Noise Print

The Set Noise Print command lets you select part of an audio file containing only the noise that you want to remove as a “noise print.” The noise print provides a signature of the frequencies to reduce or remove from the file.

Setting the noise print before reducing noise is optional. If you do not set a noise print before using the Reduce Noise command, Soundtrack Pro extracts a noise print from the selected part of the audio file. If there is an existing noise print, it will be used, even if it is from a different audio file, unless you set a new noise print.

To set part of an audio file as a noise print
  1. In the waveform display, select the part of the audio file containing only the noise you want to reduce.

  2. Choose Process > Noise Reduction > Set Noise Print.

    The selected noise is stored as a noise print.

    Note: The noise print is saved along with the Soundtrack Pro project, allowing you to use different noise prints in different projects without saving presets. If you wish to work with multiple noise prints in a single project, or across multiple projects, see Save a Noise Print Preset.

Save a Noise Print Preset

In a normal workflow, Soundtrack Pro only stores a single noise print at a time. Every time a new noise print is set, any previous noise print is overwritten. If you wish to work with multiple noise prints, each one must be saved as a preset.

To save a noise print preset
  1. In the waveform display, select the part of the audio file containing only the noise you want to reduce and save as a preset.

  2. Choose Process > Noise Reduction > Set Noise Print.

  3. Choose Process > Noise Reduction > Reduce Noise.

    The Reduce Noise HUD appears.

    Figure. Reduce Noise HUD.
  4. Click the Show Presets button.

    The Presets pane appears.

    Figure. Presets pane in the Reduce Noise HUD.
  5. Click the Add (+) button at the bottom of the Presets pane.

    A new, untitled preset appears under User Presets.

  6. Type a name for the preset, and press Enter.

Load a Saved Noise Print Preset

Once a noise print preset has been saved, it can be loaded and reused at any time.

To load a saved noise print preset
  1. Choose Process > Noise Reduction > Reduce Noise.

    The Reduce Noise HUD appears.

  2. Click the Show Presets button.

    The Presets pane appears.

  3. Select the preset you wish to apply from the Presets list.

    Figure. Presets pane in the Reduce Noise HUD with a selected preset.
  4. Press the Apply Preset button.

    The saved preset is loaded.

Reduce Noise

The Reduce Noise command uses the frequency content of the noise print to reduce noise in the audio file or selection.

To reduce noise using the noise print
  1. In the waveform display, select the part of the audio file in which you want to reduce noise.

  2. Choose Process > Noise Reduction > Reduce Noise.

    The Reduce Noise HUD appears.

    Figure. Reduce Noise dialog.
  3. In the Reduce Noise dialog that appears, you can optionally set the following:

    • The noise threshold: The noise threshold determines the level below which audio in the noise print is considered to be noise. Lowering the threshold results in only very low signals being reduced, while raising the threshold results in more high-level signals being reduced.
    • The tone for noise reduction: The Tone Control slider controls whether low-frequency content (bass) or high-frequency content (treble) is preserved during noise reduction.

    You can also preview the noise reduction with the dialog open.

To set the threshold of the noise reduction
  • In the Reduce Noise dialog, drag the Noise Threshold slider left to lower the threshold, or drag it right to raise the threshold. You can also type a value (in decibels) in the Noise Threshold field.

To set the amount of noise reduction
  • Drag the Reduction slider left to decrease the amount of noise reduction, or drag it right to increase the amount of noise reduction.

To change the tone of the noise reduction
  • In the Reduce Noise dialog, drag the Tone Control slider left to preserve more low-frequency content (bass), or drag it right to preserve high-frequency content (treble) during noise reduction.

You can preview noise reduction with the Reduce Noise dialog open and adjust the threshold and tone of noise reduction. You can also hear the audio file or selection with and without noise reduction, or hear only the noise to be removed.

To preview the file with noise reduction
  • Click the Play button in the lower part of the Reduce Noise dialog.

To set the preview volume level
  • Drag the Volume slider in the lower part of the Reduce Noise dialog left to lower the volume or right to raise the volume.

To compare the file with and without noise reduction
  • Click the Bypass button to hear the file without noise reduction. Click the button again to hear the file with noise reduction.

To hear only the noise to be removed
  • Select the Noise Only checkbox.

To use a noise reduction preset
  1. In the Reduce Noise dialog, click Show Presets.

    The Presets drawer appears.

  2. In the Presets drawer, select a preset from either the Factory Presets or User Presets list.

  3. Click Apply.