Caruso’s vocal transformation started in the 1907 when he first began to sing Verdi's opera, Aida. This opera is notoriously difficult for the tenor. It requires a robust and resilient voice to compete successfully with Verdi's dense orchestration, as well as one with the facility to take on its challenging melody lines (which at times rest uncomfortably high, for example, in the tenor aria Celeste Aida). As Caruso began to sing Aida on a regular basis, music critics and fans alike began commenting on the “change” in his voice. To anyone’s ear, his voice became noticeably bigger, heavier, and more resonant, while still retaining its remarkable flexibility and agility. The continual challenge of performing Aida clearly initiated a voice building phase in his career, and as he began taking on more dramatic roles, his voice continued to evolve, which eventually matured into the astounding instrument that we hear in 1920.
If we listen to any of his recordings from the very early years of the 20th century, say Una Furtiva Lagrima, for example, and compare this voice with that of his 1920 recording of Halevy’s Rachel, Quand Du Seigneur from his opera La Juive, the change in his voice is not only surprising, it’s simply mind-blowing. In the earlier aria, his voice sounds relatively light and bright—a typical lyrical tenor sound (even taking into account that he intentionally lightened his voice to meet the lyrical requirements of the aria). In the 1920 recording, by contrast, his voice resounds with deep baritonal—almost bass-baritonal—depth and resonance, yet it also possesses penetrating, tenorial brilliance (squillo) and explosive high notes. His mature voice became, in short, a veritable force of nature. At that point, the divine couplet had become fully mobilized in his throat. Once again it must be stressed that, despite his radical vocal transformation, he was still a master of employing subtle color and dynamic shifts when he chose. In his rendition of Pieta Signore by Stradella, that he recorded 1918, we hear an example of his finely controlled vocal shading. But the Caruso voice became much more than just a supremely muscular instrument.
Caruso’s son, Enrico Caruso Jr., in his book about his father—Enrico Caruso: My Father and My Family—said that despite the astounding power and fullness of Caruso’s voice, his tone had a characteristically “ingratiating softness” to it. As we mentioned more than once, most large voices lack tenderness of expression and the capacity to phrase delicately with finely graded tonal colors. As we saw, Caruso was a remarkable exception to a general rule. Before Caruso graced the stage, tenors also tended to be stiff, stilted, and restrained in an unnatural way—and polished to the point of erasing all earthliness and humanity from their singing. Caruso stood opera singing on its head: his singing was natural and spontaneous with real-life passions, and he communicated directly in precise and clear language, never through detours into artificial art. Unlike any opera singer before or since, the colorful textures and emotions of his voice shimmered with human understanding, and despite the intensity of his passion, Caruso never allowed his singing to lose its nobility, clarity, and simplicity.