When guitar maker Paul Reed Smith strums one of his creations, the vibrations of its strings are greater than just the audible notes and harmonies they emit.
Smith and his father, former government mathematician Jack Smith, first demonstrated those complex harmonics more than a decade ago. Technology they developed and patented produces an intricate picture of the layers of waves that come together to produce a unique sound, illustrating why a single note doesn't sound the same on different instruments.
But it can do more than that. After his father died nine years ago, the younger Smith realized that in the same way it measures sound in precise detail, the technology also can analyze images, video and, eventually, any other type of wave.
That realization is the foundation for Digital Harmonic, Smith's new side business that he foresees could one day rival his first brainchild, PRS Guitars. It's a far cry from producing custom guitars for famous musicians. Possible applications include improving medical imaging and making it safer for patients, analyzing intelligence data, and enhancing radar images for the military.
"If this technology can reveal all this data that's in these images, the hope with scientists and with us is that we'll be able to reduce the radiation that you would get in, say, a CAT scan or a stent operation and even get a better image," Smith said. "Reducing radiation is a pretty hot topic in medicine right now, and we believe we have technology that's going to help with that."
Digital Harmonic launched officially this month after 10 years and $10 million of investment within PRS Guitars, which Smith founded in Annapolis in 1985 and moved to Kent Island in 1996. The company has attracted $5 million in outside investment and is looking to raise $5 million more.
While Smith spent years building his business, and building the perfect instruments for the likes of Carlos Santana and Journey, he recalled his father insisting he learn the physics of sound too. Together, they created software that can break down the host of sound waves known as harmonics that combine to produce the chords and riffs for which Smith's guitars are known.
"When something vibrates, it creates harmonics," Smith said. "Very rarely in nature do you get just a single tone."
For example, Smith said, air passing across an open car window creates vibrations that occur at different speeds, but not all of them are audible to the human ear. If a person puts a hand a few inches in front of their mouth while talking, you can still hear them, but the barrier blocks out some of the waves and might make the voice tone sound different.
That sort of information is useful to more than just guitar makers and musicians.
In the realm of sound, doctors could use the technology to analyze heartbeats for signs of valve damage or heart disease. While a stethoscope can detect some abnormalities, detailed visualizations the company has created of the harmonics contained in a heartbeat can explain more, Smith said, highlighting irregular peaks and valleys in the layers of sound waves.
And the same analysis can be applied to other types of waves. Instead of breaking down the harmonics of a sound, it can scrutinize each pixel of a still or video image, measuring it and its relationships to the pixels around it using 3 billion calculations on each individual grain, Smith said.
By extrapolating the relationships between the pixels, the technology can offer a more detailed image.
"This way of measuring has taught us things we never even imagined were possible," he said. "It all started with a physics lesson."
A group of doctors and scientists who see potential applications for the technology have joined Digital Harmonic as advisers and stockholders. Many of them are oncologists at Johns Hopkins Hospital, eager to see if it could one day improve X-rays, CAT scans and ultrasounds.
To demonstrate that potential, Smith and his colleagues have applied the algorithms to medical imagery that has been sapped of four-fifths of its brightness, contrast and other information, to simulate a lower dose of radiation. The results appear clearer and more detailed than the original images.
"I think it's very promising," said Dr. William Nelson, director of the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins. "The real opportunity may be: Can you get that kind of information and image quality using less exposure to radiation?"
Still, for now, it's just a theory. Nelson cautioned he can't endorse Digital Harmonic's technology unless and until it gets Food and Drug Administration approval.
There is no firm business model in place for Digital Harmonic yet. Smith, who plans to stick full time to making guitars, is in the process of hiring a CEO to lead the spinoff company, he said. The company has a handful of employees but plans to hire more technologists once it opens a planned office in Columbia.
Smith and Shane Morris, the company's chief technology officer, are working to build the company's computing power, so it can perform its medical image analysis in real time, in operating or examination rooms. They could sell the technology to hospitals or license it to manufacturers of medical imaging equipment, Smith said.
Meanwhile, the company is entertaining other possible applications, negotiating with a defense contractor for the Navy to help refine military intelligence data, for example. One day, with a lot more capacity for data crunching, Digital Harmonic could improve radar signal definition, Morris said.
"It doesn't matter what it is," he said. "It's mathematics."