“The modern voice induces and applies resonance by means of a forward production independent of the pitch of the note to obtain a predetermined ideal resonance not naturally appropriate to the note.  Certain exercises stimulate supposed places of resonance, thereby working on the effect and not the cause of sound production, in other words putting the cart before the horse.  The result is that you sing with the voice that is predetermined and now in fashionable demand, not, however, your own individual voice, which was the fashion for several hundred years.  Blanche Arral illustrates this very clearly remembering the great voices she heard in her day:

Each of these voices had a color which was peculiar to it.  One voice might be said to be golden, another silver, one a brilliant vermillion, one a rich dark purple.  There was a wide variety in texture, color, and tone, and I attribute all this to the method of emission of which I have spoken…To my ears most of the young singers I hear now possess what we would have called in my youth la voix blanche.  This means, as well as I can describe it, a voice lacking in musical ring, lacking overtones, as they are called now, in fact having very little true tone any any sort – colorless, flat, artificial, and far from the genuine article, the true natural quality, for few voices are naturally white.

We see that Arral knows exactly why voices in 1937 sounded different compared to the voices she used to hear from her colleagues when she mentions the “method of emission” as the cause of good or bad vocal sound.  A quarter-century later Herbert-Caesari completely agreed with Arral condemning the modern “method of emission” in no uncertain terms: “The so-called ‘forward production’ method is largely responsible for the general low standard of singing, technically speaking, and for the ruin of innumerable voices. Its history is inglorious. It is invariably wedded to that obsession: Diaphramatic drive. The nefarious marriage has wrought untold harm.”
Bloem-Hubatka, Daniela. The Old Italian School of Singing: A Theoretical and Practical Guide. McFarland, 2012.