It is, indeed, the very opposite of it." Nasal tone quality and nasal resonance must not be confounded.

A nasal tone is constricted, while a tone with nasal resonance is free.

Again, a tone may be unmarred by the nasal quality, yet if it lacks nasal resonance it lacks vibrancy, carrying power.
Nasal tones are produced, not because the vibrations pass through the nasal passage, but because they are obstructed in their passage through them.

A nasal tone is always a cramped tone, due to impediment, tension, or muscular contraction, particularly in the nasopharynx.
The congestion and consequent thickening of the mucous membrane lining the cavities of the nose and head, resulting from a cold, make the tone muffled and weak, owing to the inability of the parts to respond to the vibrations and add to the tone normal nasal resonance.
The elder Booth (Junius Brutus), about 1838, suffered from a broken nose which defaced his handsome visage and spoiled his splendid voice.
His disability was so great that afterward he seldom played.

That the cause of this impairment of Booth's voice was due to the contraction and more or less complete obstruction of the nasal passages is too evident to call for comment.
Many singers have sweet but characterless voices that lack the fulness, power, and ring they might have because they fail to avail themselves of the augmenting power of the resonance cavities.