Auto-tune inventor Andy Hildebrand returns to ECE ILLINOIS

To support himself during his graduate school days at Illinois, ECE alumnus Andy Hildebrand (MSEE ’72, PhD ’76) applied his expertise in computers and estimation techniques while working at the university’s former Office of Long Range Planning and Analysis.

But he never planned on what he observed forty years later.

“I don’t even recognize the place,” said Hildebrand on seeing the campus this fall—his first visit since earning his doctorate and going to work for Exxon in Texas in 1976.

Nor had he planned on making his mark far afield from the oil industry, with an invention that forever changed the world of pop music.

Hildebrand’s 1996 brainchild, a real-time audio pitch-correction system called Auto-Tune, has its defenders and detractors among artists, fans, and critics. However, all agree that Auto-Tune elegantly solved a nettlesome problem once faced by recording industry engineers and producers—the need to do many takes of a given song and splice them together to get the right pitches from beginning to end.

That’s why Auto-Tune is essential in studios today. That’s why Hildebrand has been featured in media outlets from Priceonomics to PBS Nova. And that’s why he was invited to give an ECE Colloquium talk, “Mathematics behind Auto-Tune,” in Urbana on Sept. 15, 2016.

In tune with Illinois

Originally from Coronado, California, Hildebrand went to Michigan State for undergrad, earning a bachelor’s in systems science and subsequent employment as a civil servant with the Naval Ships Engineering Center in Washington, D.C. There he worked on inertial navigation and contributed to the SRN-9 navigation system, a precursor to GPS.

“The receivers weighed a ton and took up a rack six feet high,” Hildebrand recalled. “Now, it’s on a chip in your phone.”

But what interested him more than the hardware was the advanced mathematics involved, such as Kalman filtering and estimation theory. He decided to go to graduate school and learn more.

And it turns out that Illinois—though famously flat—was right in tune with Hildebrand’s aspirations.

“Illinois had a great reputation. And they didn’t, at the time, require the GRE [Graduate Record Examination], which I hadn’t bothered to take, but they did admit me based on my record. So I chose Illinois.”

The burgeoning Decision and Control group within Illinois’ Coordinated Science Laboratory provided an ideal home for Hildebrand, with his mathematical bent and interdisciplinary outlook. He gravitated to now-Emeritus Professor William Perkins, who advised Hildebrand’s master’s thesis on state estimation in systems with unknown noise inputs.

“He was very clear, very systematic. He was also very human,” said Hildebrand of Perkins, his favorite teacher at Illinois.

Pest control

“I have an interest in everything; I ask a lot of questions,” says Hildebrand. One day, he was discussing the problem of agricultural pest control with a friend in the Department of Entomology. The friend told him how, with rising awareness of the dangers of pesticides, farmers needed to use the chemicals more intelligently, but to do so required better knowledge of the pest population dynamics.

“The idea of technology and farming was really interesting to me,” Hildebrand said. “I thought I could do something about that because there was this technology developing for semiconductors—it started out in heat transfer, but now it’s in semiconductors—called diffusion theory. It has a lot of applications, including insect growth patterns and growth stages. So the diffusive variable was not space, but it was now age. And the equations fit, so we applied it.”

That project, applied specifically to the alfalfa weevil, became Hildebrand’s PhD dissertation. His defense was chaired by ECE and CSL Professor Abraham Haddad, who is now emeritus at Northwestern University.

“He had a pretty open mind,” Hildebrand said of Haddad. “He was very theoretically oriented, so he and I would have some lively talks about what I should be doing … because I’m very practically oriented.”

Listen to the music

At Exxon, Hildebrand applied related advanced math techniques to the processing of massive data sets collected in seismic surveys. In 1982, he and three others founded Landmark Graphics, which built and sold 3D graphic workstations to oil companies and others who needed to interpret seismic data. The foursome shared the 1999 Cecil Green Enterprise Award from the Society of Exploration Geophysicists in recognition of their product, which became standard equipment for oil companies .

“I often describe it as standing outside in a thunderstorm, listening to the thunder, and then computing the shape of the clouds,” Hildebrand said of his geophysical work. “The education at Illinois was the starting place. All that I was doing in the area of geophysics was building from that.”

By 1986, Hildebrand—a lifelong musician—was reverting his efforts back to a different kind of listening. He studied music at Rice University and began composing with sampling synthesizers, which he found woefully deficient. The seeds of Auto-Tune were planted.

He left Landmark Graphics in 1989 and the next year founded Antares Audio Technologies. The company supplied digital signal processing-based products to the music industry, the most significant being Auto-Tune in 1996. The rest is history.

Carrying it forward

During his recent visit to campus, Hildebrand got a sense of the elite company he keeps as a University of Illinois contributor to the world of electronic music.

The day began with a demonstration of the Continuum Fingerboard by its inventor, ECE lecturer Lippold Haken. Emeritus professor Jim Beauchamp then escorted Hildebrand to the University Library’s Sousa Archives and Center for American Music, where a functioning recreation of Beauchamp’s early synthesizer, the Harmonic Tone Generator, is on display next to Salvatore Martirano’s legendary Sal-Mar Construction. The tour ended with a visit to the School of Music’s historic Experimental Music Studios, founded in 1958 by the first composer of computer music, Lejaren Hiller.

Hildebrand recalled playing flute in one of the music school orchestras during his time at Illinois. But the foundation that led to Auto-Tune was laid north of Green.

“The value of U of I for me was as a training ground,” he said. “It gave me a lot of depth and a lot of breadth, both in engineering and mathematics, and that’s what I carried forward.”

Now approaching age 70, Hildebrand plans to sell Antares, where he is known affectionately as “Dr. Andy.”  He and his wife will soon move far away from company’s home base in Scotts Valley, California, to Puerto Rico. Both the seller and his potential buyers are interested in a research and consulting role for the company’s founder, who anticipates spending more time on hobbies like woodworking and archery.

It’s good to know the doctor will still be in.