Underlined portions are emphasized by the blogger:

…with stories of Duprez’s triumph ringing in our ears, it is surprising to read that, according to Diday and Pétrequin, ‘those who heard the darkened singing for the first time were unanimous in saying that it was a type of voice that was forced, false, artificial.’ (‘Les personnes qui entendirent pour la première fois le chant sombré furent-elles unanimes à dire que c’était un genre de voix forcé, factice, artificiel.’ [311]). The voix sombrée is, in a word, pathological. This judgement has two meanings for the Mémoire’s two audiences. For scientists, the pathological status of the voix sombrée is a matter of observed fact: it is the result of an imbalance in the normal equilibrium of the forces of phonation as they were conceived of at the time. The larynx is lowered, airflow is increased, energy expended is magnified – the picture of voix sombrée painted in the Mémoire bears the distinctive marks of what Georges Canguilhem has identified as the new conception of pathology in the early nineteenth century, ‘the quantitative modification of the normal.’(1) For the essay’s musical readership, the voix sombrée is pathological in a more vernacular sense: a practice deleterious to art and dangerous for singers which, though it serves a particular purpose, must be contained, managed, kept under control. The Mémoire ends with the ringing conclusion that, for rigorous physiological reasons, the practice of voix sombrée was destined to die out, and soon.

Bloch, Gregory W. “The pathological voice of Gilbert-Louis Duprez.” Cambridge Opera Journal 19.01 (2007): 11-31.

(1) Georges Canguilhem, The Normal and the Pathological, trans. Carolyn R. Fawcett (New York, 1989). Part 1 of the book, first written in 1943, is entitled, ‘Is the pathological state merely a quantitative modification of the normal state?’.