Using Frequency Spectrum View

When you first open the File Editor, it shows the audio file in Waveform view. You can also view and edit an audio file in Frequency Spectrum view. Frequency Spectrum view gives you a way to find areas of significant frequency change that aren’t visible in a waveform.

Viewing an Audio File in Frequency Spectrum View

In Frequency Spectrum view, the display shows the frequency spectrum of each channel of a stereo audio file on a scale from 0 Hertz (Hz) to half the sample rate of the file. For example, for a 48 kHz audio file, the scale progresses from 0 Hz to 24 kHz.

To view an audio file in Frequency Spectrum view
Do one of the following:
  • Choose View > File Editor Display > Show Spectrum.

  • Click the Frequency Spectrum View button in the upper-right corner of the File Editor tab or the File Editor project view.

    Figure. Toolbar showing the Waveform View button and the Frequency Spectrum View button, with the Frequency Spectrum View button selected.

The display changes to show the audio file’s frequency spectrum.

Figure. File Editor window showing Frequency Spectrum view.

You can select parts of the audio file, apply actions, and edit the audio file in Frequency Spectrum view in the same way as in Waveform view. In addition, you can make selections of frequency ranges as well as copy, paste, delete, and adjust the amplitude of frequency selections. You can also change the Frequency Spectrum view display to show the frequency spectrum linearly or logarithmically, use different analysis windows, and change the number of samples used to calculate the view.

To return to Waveform view
Do one of the following:
  • Choose View > File Editor Display > Show Waveform.

  • Click the Waveform View button.

Using the Spectrum View HUD

The Spectrum View HUD is a floating window that provides extensive controls for Frequency Spectrum view.

Figure. Spectrum View HUD window.
  • Preemphasis slider and value field: Applies gain per octave. Higher values emphasize high frequency content.
  • Minimum Frequency slider and value field: Allows you to view a subset of the frequency range (for example, only the frequencies over 1 kHz).
  • Maximum Frequency slider and value field: Allows you to view a subset of the frequency range (for example, only the frequencies under 9 kHz).
  • Minimum Power slider and value field: Defines the bottom of the scale (where the blue portion of the gradient starts).
  • Maximum Power slider and value field: Defines the top of the scale (where the red portion of the gradient ends).
  • Analysis Window pop-up menu: To display the audio file in Frequency Spectrum view, part of the audio data for each given point in time is analyzed. Each method of analysis represents a slightly different compromise between frequency resolution and spectral leakage. You can choose between several different analysis methods, called analysis windows, used to display the frequency spectrum in Frequency Spectrum view.
  • Window Size pop-up menu: The number of samples used for Frequency Spectrum view. This parameter trades off frequency resolution for time resolution. Smaller window sizes are more accurate timewise, but smear frequency information across adjacent frequencies (vertical lines, or transients, appear sharper). Larger window sizes provide a more accurate frequency display, but will smear things horizontally (horizontal lines appear sharper, but transients are smeared).
  • Frequency Scale buttons: Use Frequency Scale to switch between linear display (in which harmonics appear evenly spaced) and logarithmic display (in which octaves appear evenly spaced).
  • Color pop-up menu and gradient slider: Use the menu and slider to customize the gradient for Frequency Spectrum view.
  • Reset button: Resets all controls to their default values.
To open the Spectrum View HUD
  1. Turn on Frequency Spectrum view.

  2. Do one of the following:

    • Choose View > File Editor Display > Show Spectrum Controls.

    • Control-click the spectrum display, then choose Show Spectrum Controls from the shortcut menu.

Adjusting the Frequency Spectrum View with the Shortcut Menu

You can also Control-click the Frequency Spectrum view to change the settings.

To show the frequency spectrum on a logarithmic scale
  • Control-click the Sample ruler along the left edge of the display, then choose Logarithmic from the shortcut menu.

To show the frequency spectrum on a linear scale
  • Control-click the Sample ruler along the left edge of the display, then choose Linear from the shortcut menu.

To display the audio file in Frequency Spectrum view, part of the audio data for each given point in time is analyzed. Each method of analysis represents a slightly different compromise between frequency resolution and spectral leakage. You can choose between several different analysis methods, called analysis windows, used to display the frequency spectrum in Frequency Spectrum view.

To choose an analysis window for Frequency Spectrum view
  • Control-click the spectrum display, then choose an analysis window from the upper part of the shortcut menu.

    Figure. Spectrum display shortcut menu, with Triangle chosen.

Frequency Spectrum view changes the display using the analysis window you selected. Experiment with these options to see which one shows the data the best.

You can also choose the number of samples used to calculate the spectrum display.

To choose the window size (number of samples used) for Frequency Spectrum view
  • Control-click the spectrum display, then choose a number from the lower part of the shortcut menu.

Editing in Frequency Spectrum View

Use the Frequency Spectrum view and the Frequency Selection tool to select frequency ranges as well as to copy, paste, delete, and adjust the amplitude of frequency selections. You can also select parts of the audio file, apply actions, and edit the audio file in Frequency Spectrum view in the same way as in Waveform view.

To select a frequency range
  1. Turn on Frequency Spectrum view.

  2. Click the Frequency Selection Tool button at the top of the File Editor tab or the top of the File Editor project view.

    Figure. Toolbar with Frequency Selection tool button selected.

In general, editing in Frequency Spectrum view uses the same conventions as editing in Waveform view. For more information about editing in Waveform view, see Using the Global Waveform View.

Figure. File Editor showing a selected area in Frequency Spectrum view.

Guidelines for Using the Frequency Selection Tool

Here are some further guidelines for editing in Frequency Spectrum view with the Frequency Selection tool:

  • All paste edits, including paste, paste mix, and paste repeat, are supported for frequency selections.

  • Pasting to an ordinary (full frequency range) selection follows the same conventions as in the Waveform view.

  • Pasting to a narrow frequency range causes the contents of the Clipboard to be filtered before being pasted. This filtered result is added to the result of applying the complementary filter to the original audio with any necessary truncation or zero-padding if the length of the selection is greater than or less than, respectively, the length of the Clipboard audio data.

  • When you switch between Frequency Spectrum view and Waveform view, ordinary (full frequency range) selections are preserved, but any narrow frequency range selections are reset.