your brain

Picking up a little bit on Justin’s post from Friday, I’m reading a book right now called This is Your Brain on Music – The science of a human obsession by Daniel J. Levitin. Levitin is a former successful music producer and engineer who got so fascinated with how people perceive music that he went back to school and got a Ph.D. in neuroscience. If I were a real blogger with a real blogger’s conscience, I’d write a proper review of this book because it’s awesome and deserves a more thorough discussion. I’m less than halfway through it, though, so a review would be premature at this point. I just want to talk about a few points he raises in the book.

The first 80 pages or so are spent defining the basic elements of music for the non-musician. One of the obvious upshots of this whole first section is that everyone is a music machine, whether they consider themselves to be or not, and that we acquire a sort of musical language and culture in ways that are poorly understood but seem similar to language. He says in the first pages that musicians might want to skip this introductory discussion of the elements of music, but I wouldn’t recommend skipping anything here. I have been studying, performing, and producing music pretty intensely my whole life, and I learned things from this section of the book about pitch, timbre, melody, rhythm, etc. that I hadn’t ever considered.

For example, the discussion of pitch gives just enough detail to convey the complexity of the issue without being completely overwhelming to the newcomer. I had always thought of pitch in a fairly simplistic way, roughly equivalent to the fundamental frequency of a tone, but apparently this is not the case. Pitch is, according to Levitin, a purely psychological phenomenon, not a physical one. He says sounds have no pitch until our brains get involved. In fact, if I’m reading him correctly, he says there is no sound until our brains get involved – until then, there are only vibrating molecules of air. This is a pretty interesting concept for me and it gets even more interesting when he starts talking about how our brains learn how to group sounds together to form coherent gestalts. Before he gets to that point in the discussion, though, he talks about the special relationships our brains have to pitch. Here’s what he says about this:

“After sounds enter the ear, they pass by the basilar membrane, where certain hair cells fire, depending on the frequency of the sounds. The membrane acts like a motion-dector lamp you might have in your garden; activity in a certain part of the membrane causes it to send an electrical signal on up to the auditory cortex. The auditory cortex also has a tonotopic map, with low to high tones stretched out across the cortical surface. In this sense, the brain also contains a “map” of different pitches, and different ares of the brain respond to different pitches. Pitch is so important that the brain represents it directly; unlike almost any other musical attribute, we could place the elctrodes in the brain and be able to determine what pitches were being played to a person just by looking at the brain acitivty. And although music is based on pitch relations rather than absolute pitch values, it is, paradoxically, these absolute pitch values that the brain is paying attention to throughout its different statges of processing.

This direct mapping of pitch is so important, it bears repeating. If i put electrodes in your visual cortex (the part of the brain at the back of the head, concerned with seeing), and I then showed you a red tomato, there is no group of neurons that will cause my electrodes to turn red. But if I put electrodes in your auditory cortex and play a pure tone in your ears at 440 Hz, there are neurons in your auditory cortex that will fire at precisely that frequency, causing the electrode to emit electrical activity at 440 Hz – for pitch, what goes into the ear comes out of the brain!”

He then gets into an even more mindblowing discussion of timbre, wherein he talks about the phenomenon of the restoration of the missing fundamental. I couldn’t believe I’d never heard about this, and now I can’t stop thinking about it. Apparently if you hear a tone composed of a normal set of physically realistic overtones and you strip out the fundamental frequency (or the note’s pitch), your brain will calculate from the overtones the fundamental frequency that should have been there and will restore it into your mental perception of the note. You can even deviate somewhat from the frequencies in the harmonic series and your brain will sort of interpolate to find the fundamental frequency that best fits the series. He then tells of a graduate student, Petr Janata, who tested this phenomenon by putting electrodes in an owl’s brain. He played for the owl a version of Strauss’s “The Blue Danube Waltz” that had the fundamental frequencies missing from the notes.

“Petr hypothesized that if the missing fundamental is restored at early levels of auditory processing, neurons in the owl’s inferior colliculus should fire at the rate of the missing fundamental. This was exactly what he found. And because the electrodes put out a small electrical signal with each firing – and because the firing rate is the same as a frequency of firing (as we saw above) — Petr sent the output of these electrodes to a small amplifier, and played back the sound of the owl’s neurons through a loudspeaker. What he heard was astonishing: the melody of “the Blue Danube Waltz” sang clearly from the loudspeakers: ba da da da da, deet deet, deet deet. we were hearing the firing rates of the neurons and they were identical to the frequency of the missing fundamental.”

Whoa. This might be old news, but it was new to me. I can imagine all sorts of interesting things you could do by putting electrodes in people’s brains, putting headphones on them, and then hooking their brains up to loudspeakers and listening to their brains. I wonder what the output would sound like if you did this with 10 people simultaneously processing the same input. If this were legal, it could be all sorts of fun.

I can totally see why this guy left the world of music to study this stuff.

The other thing that struck me was the story of his interactions with the famous engineer, John R. Pierce, of Bell Labs and an early faculty member at Stanford’s computer music center, CCRMA. Pierce is one of those people who is such a badass that you can’t figure out which major accomplishment to list first when trying to briefly characterize him. He supervised the team of engineers who built and patented the transistor, and he apparently named it. He is also credited with inventing the traveling wave vacuum tube, and he launched the first telecommunications satellite, Telestar. He co-invented a tuning called the Bohlen-Pierce scale. He was a true innovator. Here’s Levitin’s Pierce story:

“I first met Pierce in 1990 when he was already eighty and was giving lectures on psychoacoustics at CCRMA. Several years later, after I had earned my Ph.D. and moved back to Stanford, we became friends and would go out to dinner every Wednesday night and discuss research. He once asked me to explain rock and roll music to him, something he had never paid any attention to and didn’t understand. He knew about my previous career in the music business, and he asked if I could come over for dinner one night and play six songs that captured all that was important to know about rock and roll. Six songs to capture all of rock and roll? I wasn’t sure I could come up with six songs to capture the Beatles, let alone all of rock and roll. The night before he called to tell me that he had heard Elvis Presley, so I didn’t need to cover that.

Here’s what I brought to dinner:

1) “Long Tall Sally,” Little Richard
2) “Roll Over Beethoven,” the Beatles
3) “All Along the Watchtower,” Jimi Hendrix
4) “Wonderful Tonight,” Eric Clapton
5) “Little Red Corvette,” Prince
6) “Anarchy in the U.K.,” the Sex Pistols

…Pierce listened and kept asking who these people were, what instruments he was hearing, and how they came to sound the way they did. Mostly, he said that he liked the timbres of the music.”

I don’t know why this story amuses me so much, but it’s hilarious to me. Just the thought of having to introduce all of rock music in 6 songs to a genius whose primary experience with music is through physics and perhaps classical music…I don’t know. It cracks me up. Maybe because I’ve worked with old guys like this who are so out of touch with popular culture that I can imagine how this scenario would play out.

It also made me think about which six songs I would come up with (minus Elvis) to “capture all of rock music.” I doubt I would think of any of these. What songs would you choose?