General Remarks

Spectral graphs can be viewed in two different ways: using a full size spectral analysis dialog equipped with a 512-point graphic display or using a reduced size dialog with a 128-point display.

The extended dialog allows one to choose among the available spectral estimation methods (FFT, AR) as well as to select the scale (linear, logarithmic) and the mode of display (automatic normalization, automatic updating). The full size window allows for precise reading of the plots (the value of the spectral density function for a particular frequency). The reduced size dialog can be used for fast spectrum previewing.

You can switch between the two dialogs at any time by means of pressing the MINIMIZE/MAXIMIZE button, situated in the upper right corner of each window. Whenever you select the Spectrum command available from the Toolbox menu, or press the SPECTRUM button, situated on the toolbar the spectral analysis dialog will be shown on the screen in the last-used form (i.e. if you close the reduced size dialog and press the SPECTRUM button the small dialog will appear again).

The material for spectral analysis is always taken from an active soundfile. If the Auto switch is on, i.e. the analyzer works in the automatic update mode, the processed fragment is centered around the current cursor position and spectral graphs are redrawn each time you change position of the cursor within an active soundfile or switch between different soundfiles. If your computer is fast enough you can watch the spectrum changing while the soundfile is played back (for slower machines problems with skipping may occur).

When a block of samples is marked in an active soundfile and the Auto box is unchecked (and only in this case), DART XP Pro will display an average spectrum of a selected portion of the audio material each time you press the Update button.

Finally, when you press the SPECTRAL VIEW button (situated between the Update button and the Close button) DART XP Pro will show how the signal spectrum evolves over time’ i.e. it will display a sequence of spectral graphs corresponding to different time instants.