Spectral characterization of ciliary beating Biological meaning of the spectral linewidth

The ciliary beating frequency in tissue culture from frog palate and lung was examined optically. Consecutive segments of the analog signal were then fast-Fourier transformed (FFT). The optical signals were measured as a function of the number of cilia by varying the examined area from 1.2 to 122 υm². The frequency of the maximum power of the spectra was independent of the measured area, while the line shape of the spectra and distribution of the main frequencies were strongly dependent on the dimensions of the area examined. The possibility that the width of the measured spectral peak reflects both the distribution of the beating frequencies and the distribution of the phases within the examined area is discussed.