Histograms of the population of correlation coefficients for each metrical relationship examined (A, Amplitude; B, Peak; C, Duration). All bins are 0.1 wide. No grouping of the cells was apparent for any of the individual relationships. In other words, there appeared to be a continuum from very weak correlations to strong positive correlations for each of the metrics. Three cells had strongly negative correlations to duration, but none of these correlations was significant (P > 0.05).