The "dual klepsydra model" (DKM) of internal time representation successfully models duration reproduction data, but relations between the DKM-based parameter kappa ("loss rate") and procedural variables (presentation modality) or individual characteristics (cognitive indices, age, sex) remained as yet unexplored. For that purpose, were-analyzed data from an earlier time reproduction study (N = 100), using visually or acoustically presented intervals of 1-5 sec. duration. Typical values of parameter kappa were approximately 0.03-0.04 sec.(-1), corresponding to relaxation times of internal "lossy integrators" of approximately 30 sec. Significant effects of presentation modality (smaller kappa values for the visual reproduction task) and of age (greater kappa in acoustic reproduction with increasing age) were observed. Cognitive variables (working memory, general fluid reasoning, attention) and sex of participants were not associated with kappa. Cognitive functions seem to play only a minor, if any, role at the level of time representation addressed by the DKM.