Stanford’s CCRMA: The Forefront of Sound and Science
A high caliber research university like Stanford makes millions of dollars in royalties each year—all coming from companies and technologies developed there. You may think this money all comes from biomedical discoveries, Google, or other tech startups. However, one of Stanford’s most lucrative inventions actually came from research in music and sound. If you’ve listened to any music written in the 80’s or later, chances are you’ve heard this Stanford invention in action.
Nestled atop a grassy hill is a beautiful brick building that houses CCRMA, Stanford’s Center for Computer Research in Music and Acoustics. CCRMA (pronounced “karma”) has its roots in a small group of programmers and musicians working in Stanford’s Artificial Intelligence lab in the 1960s. This was all in an era where computers were scarce and programs were still written on punch cards. Since CCRMA’s official establishment in 1975, it has played a key role in developing the now ubiquitous nature of digital audio.
“As someone plays music on a computer, plunks keys on a keyboard, or streams songs over the Internet, chances are good that a CCRMA alum or partner is involved in some way.”
This quote from Andrew Nelson’s book, The Sound of Innovation: Stanford and the Computer Music Revolution, reflects the many notable achievements in music and sound that came through CCRMA in its early years. Chris Chafe, current director of CCRMA, describes some of the big breakthroughs to come through the center: audio to digital conversion, early versions of surround sound, the first sound sampler, and the drum machine.
All of these technologies eventually had big impacts on music and sound-based industries, but one of CCRMA’s methods of sound synthesis enjoyed a particularly rapid commercialization and implementation in the music industry. This technique was known as Frequency Modulation synthesis.
In 1967, John Chowning discovered Frequency Modulation (FM) synthesis at CCRMA, a technology that would drive the sound of the 80’s. FM was behind the chiming bells, woody marimbas, pulsating bass synths, and many other iconic sounds of this time. An array of sounds in modern pop music has also been created with FM synthesis. FM synthesis works through a process called modulation to alter the tonal qualities of a sound wave. To fully understand how this works, it’s important to first build a solid understanding of sound.
The purest form of sound can be represented as a sinusoidal wave. The pitch of a sine wave is determined by the frequency, or the number of times a wave oscillates in a second. So if a sine wave repeats 440 times per second, its frequency is 440 Hertz (perceived by our ears as the pitch of “A”). Higher frequencies equate to higher pitches of notes.
Normally a sine wave produces only one frequency, which is called the fundamental tone. Imagine the sound of a flute. This “pure” sound is actually very similar to the sound of a sine wave. Now imagine a clarinet. The sound of a clarinet is more sonically complex, producing a dense, “woody” sound. This is determined by a series of sine waves called partials, which oscillate at different frequencies from the fundamental wave. While the fundamental wave determines the pitch of a note, partials determine the timbre, making a flute and clarinet differentiable.
Frequency Modulation works by modulating, or repeatedly altering, a sine wave with another high frequency wave. The sound output wave is called the carrier, while the wave performing the modulation is called the modulator. The modulator is never actually heard as a tone, but its effects on the carrier are.
In FM synthesis, modulation of a sine wave creates unique combinations of partials to produce different types of sound. For example, a sine wave may produce a frequency of 440 Hz, but if this wave were modulated at 600 Hz, it will also produce an extra set of sideband waves to give the tone a different sound quality. Try to imagine a sine function oscillating within a different, larger sine function. This is FM, and it produces the waveforms you can see in the picture below. Frequencies, amplitudes, and waveforms can all be modified to produce different sounds. The ability to manipulate so many individual parameters offers an extremely wide sonic palate. After its conception, FM synthesis was poised to become a new standard method of digital sound synthesis because of the wide sonic possibilities it offered.
In fact, back at Stanford, this technology would drive CCRMA’s early success through a long and fruitful partnership with Yamaha. In 1975, Yamaha licensed the technology from Stanford and quickly incorporated it into their DX7: the first FM synthesizer. This synth was the basis of a sonic revolution. Musicians such as Phil Collins, Tears for Fears, Michael Jackson, and Queen have all utilized FM synthesis in their music. Still today, this Stanford invention permeates music without the public’s knowledge.
Through this partnership established with Yamaha, total Stanford profits climbed to $22.9 million. This is the fourth highest revenue Stanford has made off of any invention or company. And this is just one example of CCRMA’s innovative approach to sound and music. Chris Chafe, director of CCRMA, describes some interesting directions that CCRMA now pursues today. In his own research, he is working to improve accuracy in the playback of sound. He also cited exciting work that applies a neuroscience approach to exploring our understanding of music. According to Chafe, we are “just at the cusp of some deeper evidence about musical function in the brain.” After my conversation with Chafe, one thing is certain: CCRMA does not intend to surrender its position at the forefront of music, science, and technology.
- For greater depth on the mathematical principles behind FM synthesis, check out this tutorial: https://www.sfu.ca/~truax/fmtut.html
- Nelson AJ. The Sound of Innovation: Stanford and the Computer Music Revolution. Cambridge, MA: MIT Press; 2015.
- Chris Chafe, Ph.D, Director of CCRMA, Duca family professor. (2016, November 4). CCRMA and its role in computer music [Personal interview].
- Stanford Office of Technology Lisencing. OTL. http://otl.stanford.edu/. Accessed November 13, 2016.