Studied acoustic measures of "roughness" in 90 male patients with laryngeal pathologies and 8 normal male speakers. Results indicate that acoustic correlates of a "rough" voice are not only the multiplicative variations that occur over several pitch periods, but also those that are synchronous with vocal pitch period. Although these results do not preclude the contribution of the irregular phenomena observed in the speech waveform, irregularity itself is not necessarily essential for perceptual "roughness."
Imaizumi, S. (1986). Acoustic measures of roughness in pathological voice. Journal of Phonetics, 14(3–4), 457–462. https://doi.org/10.1016/s0095-4470(19)30688-6