Bob Dylan might not be a great songwriter, Woody Guthrie said in 1961, but “that boy’s got a voice.” Now, of course, the opposite perception prevails. “The popular notion is, ‘Bob Dylan, he can’t sing,’” says music theorist Steven Rings.

To Rings, Dylan has a rich and varied voice—and the UChicago associate professor uses spectrographic images to capture the variations. Comparing spectrograms from performances of “It’s All Right, Ma (I’m Only Bleeding),” Rings illustrates Dylan’s vocal evolution.

Spectrograms show nuances lost in traditional musical notation, which reduces each fundamental frequency to a single note. Each pitch is, in fact, a composite of overtones. “Even though our ears generally can’t—and there’s no evolutionary need to—hear those overtones independently,” Rings says, “they contribute enormously to the color of a sound,” as these images reveal.

In a 1965 recording (top), Dylan’s pinched Okie sound mimics Guthrie. “The pitch itself, what we would sort of hum along to, is very weak,” Rings says, “and instead we have a big sort of cluster of upper partials and that’s one of the thumbprints of this particular nasal voice.”

A 1974 rendition (bottom) tends toward Dylan’s “country crooner” sound, painting a much different spectrographic picture. “In some ways it’s the exact reverse,” Rings says. “All of those partials are much less prominent. Instead you have this really prominent fundamental.”

Spectrograms from current performances, after more than 50 years and 3,500 concerts, look like “tattered shards,” but Rings speculates that they represent the voice Dylan has always wanted. When he heard Delta blues singers on the radio as a young man, he was “fascinated by these inscrutable voices”—much like Rings is with Dylan’s now.

[[{"type":"media","view_mode":"media_original","fid":"554","attributes":{"alt":"","class":"media-image","height":"873","typeof":"foaf:Image","width":"460"}}]]