User's Manual - Cornell Lab of Ornithology - Cornell University

Chapter 1: Getting Startedspectrogram, including the processor speed of the Macintosh, the length of thesignal, and the parameters that you specify in the Spectrogram Options dialogbox. You can switch to another application program and Canary will continueto calculate the spectrogram in the background. (If you want to cancel thecalculation of a spectrogram, click on the Pause button in the status window;the Cancel button will then become available.)The spectrogrampaneWhen the calculations are completed, the signal window is redrawn, with twoseparate panes. The lower pane shows the waveform; the upper pane showsthe spectrogram. The spectrogram displays frequency on the vertical axis andtime on the horizontal; the time axes of the waveform and spectrogram panesare aligned with each other. The darkness of the spectrogram at any giventime-frequency point is proportional to the logarithm of the sound intensity atthat point. The spectrogram is thus a type of three-dimensional plot ofintensity level against frequency and time, with the intensity levelsrepresented as shades of gray varying between white (minimum amplitude)and black (maximum amplitude). Later in this chapter you’ll see how to adjustthe minimum and maximum amplitudes displayed in a spectrogram. Thehighest frequency that can appear in a spectrogram depends on how thesignal was originally digitized (recorded) by the computer (see Appendix A).Figure 1.5. The signal window showing spectrogram and waveform panes.The SPG button on the command panel is now depressed and colored (if youhave a color monitor), indicating that the spectrogram display is turned on. Ifyou click the button again, the spectrogram is turned off, and the window isredrawn containing just the waveform pane. Once a spectrogram has beencomputed, you can turn the spectrogram display off and on again, without thedelay of recalculating it. (Canary saves the spectrogram even when it’s notshown on the screen.)Canary 1.2 User’s Manual 13