There is an American saying: “The road to Hell is paved with good intentions.” The Haitian version is more appropriate to this subject: “The road to Hell is paved and easy and the one to Heaven is a dirt road littered with snakes.” In other words, easy achievements in singing are generally short-lived, because they are usually simplistic and one-sided, ultimately leading to imbalance. Lasting results are acquired through hard work, frustration and patience. “Mask Resonance”, or more correctly, resonance feedback through sensations in the bones of the face, is such a simplistic, one-sided quick fix. However, I do not reject mask resonance. It has very significant perks. Otherwise it would not come down to us as one of the fundamental techniques of classical singing.
It is simply important to understand what is specifically associated with sensations in the mask. In my experience both as singer and teacher, I have come to understand that vibrations associated with the mask can be defined as complete glottal closure during fully compressed vocalism (when there is adequate sub-glottal pressure) . Full closure and adequate breath support are what we want. So what is the problem? The problem is that this excellent “carrot” comes with a hidden “stick.” Full closure and adequate breath pressure are equal to one half of singing–phonation. The resonance part is what is lacking, and without a sense of what is necessary here, the successes associated with mask resonance alone are usually short-lived.
As often suggested here, discovering the optimal default resonance adjustment is paramount to sustainable vocal health. The volume of the vocal tract from top of the glottis to edge of the lips must be maintained with the tongue and lips being the primary variables. This default volume of the vocal tract depends on the ability of the singer to release the larynx, soft palate, jaw and tongue to their default optimal positions, from which the most efficient vocalic articulations can be facilitated.
In short, mask resonance can be a fine tool to effectively monitor the state of efficiency in the glottis, provided that extraneous muscular activity can be neutralized. If glottal closure is achieved in an unbalanced manner, extraneous muscular activity will be the result, and ultimately that will throw the apparatus off balance and lead to vocal problems.
I will end with another saying, this time a vocal one: “The nose should be in the voice but not the voice in the nose”. This is one I have heard a lot and I am not sure of its origin. This is at the center of this discussion. When mask sensations through bone conduction can be felt while the larynx and soft palate are released and flexible then we have confirmed full glottal closure with a flexible vocal tract (ideal resonance conditions) or “the nose in the sound.” If however laryngeal tension causes a reduction in the optimal volume of the vocal tract, then nasality is the result, or “the sound is in the nose.”