An in-depth scientific analysis has studied the distinctive singing voice of Queen lead singer Freddie Mercury.

Mercury wowed audiences as Queen’s lead vocalist for just over two decades before his death in 1991. Now, a team of researchers have carefully scrutinized his vocal talents and have published their results in the journal Logopedics Phoniatrics Vocology.

Led by Christian Herbst, a voice scientist at the University of Vienna, the researchers analyzed “Freddie Mercury: The Solo Collection,” as well as 23 commercially available Queen recordings. The scientists also used an endoscopic video camera to study a rock singer brought in to imitate Mercury’s singing voice. Additionally, the experts analyzed a series of interviews given by the late Queen lead singer.

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An analysis of Mercury’s speaking voice suggests he was a baritone, according to the research. A-cappella recordings of Mercury highlighted “a surprisingly high mean fundamental frequency modulation rate (vibrato) of 7.0 Hz, reaching the range of vocal tremor.”

The scientists also identified “subharmonic vibration” in Mercury’s singing voice that likely created his famous “growl.”

“Their occurrence aids in creating the impression of a sound production system driven to its limits, even while used with great finesse,” the paper said. “These traits, in combination with the fast and irregular vibrato, might have helped create Freddie Mercury’s eccentric and flamboyant stage persona.”

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The study, however, was unable to prove claims that Mercury possessed a four-octave singing voice. The analyzed data, it said, could not conclude nor rule out that “such a phenomenon existed in Freddie Mercury’s voice.”

Nonetheless, the scientists stated that “it is not too far-fetched to conjecture that Freddie Mercury was rather skillful in adapting his laryngeal configuration to musical needs, thus exhibiting a great variability of sound timbres for enhanced musical expression.”