A numerical equivalence class of -cycles is said to be big if it lies in the interior of the closed cone generated by effective classes. We construct analogues for arbitrary cycle classes of the volume function for divisors which distinguishes big classes from boundary classes.
Brian Lehmann. "Volume-type functions for numerical cycle classes." Duke Math. J. 165 (16) 3147 - 3187, 1 November 2016. https://doi.org/10.1215/00127094-3673772