Changing Spectrum Analysis Settings

Available only in Sound Forge

Effects Menu

The commands on the Spectrum Analysis Options menu allow you to determine how spectral information is calculated and displayed.

What do you want to do?

Update the display automatically

From the Options menu, choose Auto Update to update the Spectrum Graph with any change in the cursor position or selection of the current file. A check mark is displayed next to the command when it is selected.

You can continue to make selections in the sound file with the Spectrum Analysis window open (just move the cursor or make selections as you normally would in Sound Forge).

Change FFT settings

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Use the Spectrum Settings dialog to adjust the FFT settings:

FFT Size

Time Analyzed (seconds)

Frequecy Bands

Frequency Bandwidth (Hz)

128

0.003 (128/44100)

64 (128/2)

345 (44100/128)

2048

0.046 (2048/44100)

1024 (2048/2)

22 (44100/2048)

Setting

Description

Rectangle

No window is applied. Using a rectangular window results in a very sharp peak but high leakage.

Triangle

A triangle window (also called a Bartlett or Parzen window) results in less leakage than the rectangle window.

Hamming, Hanning, and Blackman

Hamming, Hanning, and Blackman windows are commonly used in audio applications.

Blackman-Harris

Using the Blackman-Harris window results in the least sideband leakage at the expense of rounded graph peaks.

  1. Click the OK button.

View multiple spectrum graphs

The Spectrum Analysis window can display up to 64 spectrum graphs, each representing a point in time.

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Adjust the Slices displayed settings to specify the number of graphs displayed:

  1. Click the OK button to return to the spectrum graph.

  2. In the spectrum graph, drag the Slice slider to show or hide graphs from the display.

Set songram resolution

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Select the Set sonogram resolution check box and specify the number of FFT samplings used in the Sonogram. When this check box is not selected, the number of samplings is determined by the length of the selection and the FFT overlap setting.

Increasing the samplings increases the horizontal graph resolution but requires more processing time.

  1. Click the OK button.

Use logarithmic graphing

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Select the Logarithmic graphing check box to display the x-axis in logarithmic mode rather than linear mode. In logarithmic mode, more area of the graph is devoted to lower frequencies.

Logarithmic graphing affects the display only when Normal display is selected on the Display menu.

  1. Click the OK button.

Adjust the display range

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Adjust the Display Range controls:

Control

Description

Freq. Min

Specify the lowest frequency displayed in graphs when Zoom to Range is selected on the Display menu.

Max.

Specify the highest frequency displayed in graphs when Zoom to Range is selected on the Display menu.

Ceiling

Specify the highest amplitude level displayed in graphs when Zoom to Range is selected on the Display menu.

Floor

Specify the lowest amplitude level displayed in graphs when Zoom to Range is selected on the Display menu.

  1. Click the OK button.

Monitor playback

From the Options menu, choose Monitor Playback. A check mark is displayed next to the command when it is selected.

The Spectrum Graph will update in real time as the current file plays. The response of the graph will depend on the current FFT size and the speed of your computer.

Monitor an input source

From the Options menu, choose Monitor Input. A check mark is displayed next to the command when it is selected.

The Spectrum Graph will update in real time to any input to your selected sound card. This feature makes it possible to perform real-time analysis of room acoustics or other live sources.

Hold monitored data

  1. From the Options menu, choose Settings. The Spectrum Settings dialog is displayed.

  2. Adjust the Monitor Settings controls:

  1. Click the OK button.