6 
Spectra 
For spectral analysis MATLAB's spectrum subroutine was 
modified. The Welsh-Method of overlapping segments was implemen 
ted and each segment was modified by a 10% half cosine-taper. 
Both modifications allow higher estimates of the degrees of 
freedom f and hence a minimisation of the confidence intervals 
indicated by a vertical bar in the spectra. 
References 
Little, J.H., L. Shure, 1992: Signal Processing Toolbox User's 
Guide. The Mathworks, Inc., 112pp. 
Taylor, G.I., 19921: Diffusion by continuous movements, 
Proc. London Hath. Soc., A20, 196-211.