04 October 2009


i am only partway through daniel j. levitin's eye-opening book This Is Your Brain on Music: The Science of a Human Obsession. levitin is a former rock musician turned neuroscientist. in the book, he explores the connection between music -- its performances, its composition, how we listen to it, why we enjoy it -- and the human brain. he reveals how composers exploit the way our brains make sense of the world, why we emotionally attach to music we listen to as teenagers, why 10,000 hours of practice (not talent) makes virtuosos, and how insidious jingles (a.k.a. ear worms) get stuck in our heads. he argues that music is fundamental to our species, perhaps even more so than language.

here is a brief summary of the fundamental defining qualities of music (borrowing heavily from the book):

pitch -- a purely psychological construct, related both to the actual frequency of a particular tone, and to its relative position in the musical scale.

rhythm -- refers to the durations of a series of notes, and to the way that they group together into units.

tempo -- the overall speed or pace of the piece.

contour -- describes the overall shape of a melody, taking into account only the pattern of up and down movement of notes.

timbre -- (rhymes with amber) a kind of tonal color produced in part by overtones from a given instrument's vibrations, distinguishing it from the sound of other instruments.

loudness -- how much energy an instrument creates, or how much air it displaces. the amplitude of a tone.

reverberation -- the perception of how distant the source is from us, in combination with how large a room or hall the music is in.

when these basic elements combine and form relationships with one another in a meaningful way, they give rise to higher-order concepts such as:

meter -- refers to the way in which tones are grouped with one another across time, extracted from rhythm and loudness cues. (a waltz meter organizes tones into groups of three, a march into groups of two or four.)

key -- a hierarchy of importance that exists between tones in a musical piece, existing not in the world but in our minds.

melody -- the main theme of a musical piece, i.e. the succession of notes that are most salient in the mind of the listener.

harmony -- relationships between the pitches of different tones. this can mean simply a parallel melody to the primary one, or it can refer to a chord progression.

with these definitions as backdrop, levitin explores any number of assumptions we make about music, in particular how recognition of music occurs in the human brain. he asks:

"how are memories of music different from other memories? why can music trigger memories in us that otherwise seem buried or lost? and how does expectation lead to the experience of emotion in music? how do we recognize songs we have heard before?

"tune recognition involves a number of complex neural computations interacting with memory. it requires that our brains ignore certain features while we focus on features that are invariant from one listening to the next -- and in this way, extract invariant properties of a song. that is, the brains computational system must be able to separate the aspects of a song that remain the same each time we hear it, from those that are one-time-only variations, or from those that are peculiar to a particular presentation. if the brain didn't do this, each time we heard a song at a different volume, we'd experience it as an entirely different song!! and volume isn't the only parameter that potentially changes without affecting the underlying identity of the song. instrumentation, tempo and pitch can be considered irrelevant from a tune-recognition standpoint. in the process of abstracting out the features that are essential to a song's identity, changes to these features must be set aside."

to demonstrate, you will find below links to three different performances of j.s. bach's "Air on the G String" -- the first a vocal performance by bobby mcferrin; the second a violin performance by sarah chang; and the third a classical guitar performance by peo kindren. please note how our dry, academic definitions of musical qualities come alive, varying from one performance to the next, and yet the essential, identifiable piece is immediately recognizable by our brains. levitin's book explores these and many other ideas which can only broaden our understanding and enjoyment of that ephemeral experience we call music.

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