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

Chapter 3: Spectrum AnalysisFor a given frame length, different window functions will result in differentfilter bandwidths (Figure B.16). In terms of a spectrogram, this means that thevertical thickness of a line drawn to represent a pure tone will depend onwhich window function is used.Figures 3.8 and 3.9 illustrate the effect of different window functions onspectrograms and spectra of the same signal.(a)Hamming(b)Blackman(c)RectangularFigure 3.8. Effect of choice of window function on spectrograms. The signal ispart of a song of an American robin, digitized at 22.3 kHz. All threespectrograms have the same clipping level, frame length = 256 points (= 11.5mS), time resolution = 5.8 mS (frame overlap = 50%), and frequencyresolution = 10.9 Hz (FFT size = 2048 points). Filter bandwidths: (a) 353 Hz,(b) 538 Hz, (c) 174 Hz.Canary 1.2 User’s Manual 51