Select the portion of the waveform you want to analyze. The sound or note you want to analyze should be in the center of the highlighted area.
Analyzing long sections of audio can take a long time and decreases the time resolution, so your selection should be relatively short. Also, if the audio has a low amplitude level, you can boost it by using the Volume or Normalize functions.
From the View menu, choose Spectrum Analysis to show the Spectrum Analysis window if it isn’t already visible.
Use the toolbar at the top of the window to set your display options.
You can also click the Settings button in the Spectrum Analysis window to set additional options.
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). Click the Refresh button in the Spectrum Analysis toolbar to update the display. If no selection is made, analysis is performed on the samples immediately following the cursor position.
As you move the cursor through the spectrum graph, the amplitude and frequency values at the current position are displayed in a ToolTip next to the cursor and in the Statistics area at the bottom of the window:
Right-click the graph and choose Show Position from the shortcut menu to toggle the display of ToolTips. The setting for each graph in a multichannel file is independent.
If you want to display the nearest musical note equivalent of the cursor position in a ToolTip, right-click the graph and choose Show Notes from the shortcut menu:
Right-click the Spectrum Analysis window and choose Show Statistics from the shortcut menu to toggle the display of the Statistics area at the bottom of the Spectrum Analysis window.
Click the down arrow next to the Normal Display button and choose Line Graph, Filled Graph, or Bar Graph from the menu to change the type of graph displayed in the Spectrum Analysis window. A check mark is displayed next to the selected graph type.
Some video drivers have problems displaying Filled Graph and Bar Graph modes. If you encounter problems such as incorrect shading or very slow drawing, use the Line Graph option or change video drivers.
If you’re analyzing a multichannel file, you can click the down arrow next to the Normal Display button and choose Single Graph to see all channels in a single graph.
Right-click the graph and choose Logarithmic from the shortcut menu to toggle the x-axis between logarithmic and linear mode. In logarithmic mode, more of the graph is devoted to lower frequencies.
Zooming can be accomplished in several ways:
Drag on the graph to draw a box around the area you want to magnify. You can toggle through mouse selection mode by right-clicking while holding the left mouse button:
The first type is a vertical zoom window. This will allow you to zoom to a frequency range.
The second type is horizontal zoom window. This will allow you to zoom to an amplitude range.
The third type is a combination of vertical and horizontal zoom. This will allow you to zoom to a frequency and amplitude range.
Right-click the graph and choose Zoom Out Full to view the entire amplitude and frequency range.
Right-click the graph and choose Normalize dB to set the Spectrum Graph amplitude range equal to the maximum and minimum values in the graph.
Right-click the graph and choose Grab/Pan from the shortcut menu. The cursor will be displayed as a , and you can drag horizontally or vertically to scroll through the graph.
When you are zoomed into a selection of the spectrum graph, you can drag the horizontal and vertical sliders to scroll through the graph. The thumbnail image in the lower-left corner of the Spectrum Analysis window will show you which part of the graph is being displayed.
If you are analyzing a multichannel file, click the Sync button to synchronize the displays so you can view the same region of the FFT in all channels.
You can store up to four snapshots to compare multiple spectrum graphs. You can take snapshots from a single data window or from different data windows.
Snapshots are not available in sonogram display or when the Slices displayed setting in the Spectrum Settings dialog is greater than 1.
Taking a snapshot
Navigate to the portion of the graph you want to capture.
Click the Set button , and then click a snapshot button in the Spectrum Analysis toolbar.
Available snapshots buttons are displayed in black, and buttons that are in use are displayed in blue and underlined.
Showing and hiding snapshots
Select a numbered button in the Spectrum Analysis toolbar to display a stored snapshot. All selected snapshots will be displayed in the Spectrum Analysis window at the same time.
Click a selected snapshot button to exclude it from the display.
Select the Hide active plot button to hide the current spectrum so you can concentrate on your snapshots.
In the following example, snapshots 1 and 3 will be shown in the graph; snapshot 2 is hidden, and snapshot 4 is unused.
You don’t need to erase individual snapshots to update or replace them. Simply click the Set button, and then click a snapshot button in the Spectrum Analysis toolbar to update its image.
If you want to erase all snapshots, click the Clear all snapshots button .
Viewing snapshot statistics
Information about each snapshot is displayed at the bottom of the Spectrum Analysis window:
Click the Print button to print the contents of the Spectrum Analysis window, including the graph and statistics data.
Select the Auto Refresh button if you want the Spectrum Analysis display to refresh automatically updated when you change your selection in the data window.
When the button is not selected, the display is not updated until you click the Refresh button .
If you want the graph to refresh automatically during playback or input monitoring, select the Real Time Monitoring button .
Click the Real Time Monitoring button to turn real-time spectrum analysis on or off. Click the down arrow next to the button and choose a command from the menu to specify whether you want to monitor your sound card’s input or output:
When you choose Monitor Input, Sound Forge will monitor the recording devices selected on the Record page of the Audio tab in the Preferences dialog.
When you choose Monitor Output, Sound Forge will monitor the playback devices selected on the Playback page of Audio tab in the Preferences dialog.
When Monitor Output is selected, the post-processing signal is monitored when you start playback from the Plug-In Chainer.
Real-time spectrum analysis can require significant processing power. If the spectrum graph’s refresh rate seems sluggish, set the display mode to Line Graph, decrease the FFT size, or turn off snapshots.
Viewing a Spectrum Graph
Click the Normal Display button in the Spectrum Analysis window to display spectrum information as a normal spectrum graph.
The spectrum graph displays the amplitude (in dB) of each frequency component from 0 Hz to the Nyquist frequency. Frequency is displayed along the X (horizontal) axis, and amplitude is displayed along the Y (vertical) axis.
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