Spectrogram

Figure 1: Spectrogram of common loon calls. We can see how the partials (horizontal strata created by the changes in intensity of the yellow hues) are equally spaced, indicating that these calls are harmonic. The lowest stratum (in the most intense yellow) roughly corresponds to the fundamental frequencies of these calls—the pitches at which we perceive them sounding.

Figure 2: Spectrogram of the same loon calls, but in logarithmic view. Notice the unequal spacing of the harmonics (horizontal yellow strata) when shown on a logarithmic scale. This display makes it possible to see more harmonics simultaneously without sacrificing detail in how the lowest partials are represented.

Figure 3: With a smaller window size (512 samples), the oscillating pattern of the loon calls, which begin at six seconds in the figure, are rendered in higher temporal resolution. The frequency values of these calls, again as seen in the yellow strata, are imprecise because of the relatively few samples within each window where they are averaged.

Figure 4: With a larger window size (8192 samples), the temporal resolution of the loon calls beginning at six seconds is greatly reduced, however, the frequencies of their components are rendered more precisely.