One of the problems with being a musician whose instrument of choice is the piano is that it’s very difficult to take your instrument with you to parties. I mean, it’s almost impossible to find a piano carrying-case, and have you ever tried to load one into the hatchback of a Plymouth Laser? (I suppose towing it along behind the car would be a possibility, but it plays heck with the tuning…)
That’s why I’ve been thinking increasingly about taking up a new instrument: the guitar. Considering that, considering that I just spent time with a guitar-playing friend at the World Science Fiction Convention in Winnipeg (Ha! And you thought I couldn’t work WorldCon into yet a third column), and considering that Guitarman, the TV movie shot in Saskatchewan last year starring Regina guitarist Jack Semple, premieres on CBC TV tonight, this week’s column was almost inevitable.
You see, there’s a lot of science behind guitars. There’s a lot of history, too. They’re descendents of the lute, a stringed, plucked instrument that’s been played since ancient times, and emerged as a distinct instrument in Spain in the late 15th century. (The word “guitar” comes from the Arabic word “gitara,” which in turn is related to the ancient Greek word “kithara.”) Those first guitars, somewhat smaller than modern guitars and with less pronounced curves, had four “courses,” pairs of strings tuned in unison, and they quickly gained popularity all over Europe as a more easily played alternative to the lute. Late in the 16th century a fifth course of strings was added.
The modern guitar took form in the early 19th century, again in Spain: six single strings, a larger body, more pronounced bulges and geared tuning pegs. Antonio de Torres Jurado (1817-1892) is credited with creating the elegant design we know today as the “classical guitar.”
Most early guitars were strung with gut, or with both gut and metal, but in the early 20th century in the U.S. guitars with all-metal strings became popular because of their greater volume and “twangier” sound. Orville Gibson created the “arch-top” guitar, with a curved sound board to withstand the greater pressure of the steel strings, which was popular in the ’20s and ’30s, but more recently the “flat-top” steel-strung guitar has become the acoustic guitar of choice for folk and pop musicians. It’s a slightly larger, more heavily built version of the classical guitar (again, to withstand the pressure of the steel strings.)
And then, of course, there are electric guitars. More on them anon.
The science of guitars starts with the way they produce sound. Sound begins with vibration. A vibrating object sets up a compression wave in the atmosphere which radiates outward until it is dissipated or until it reaches our ears, in which case it sets our ear drums vibrating. Nerve signals inform our brains of this vibration and we “hear.”
The pitch of the sound is determined by the speed, or “frequency,” of the vibration. The pitch we know as A above middle C, for instance, results from a vibration of 440 times per second.
The source of sound on a guitar is a vibrating string. The guitar has six of them (or six pairs of two, in the case of a 12-string), which come in varying thicknesses. They’re set vibrating by the player’s finger or by a pick. A thick string vibrates more slowly than a thin string, and so produces a lower pitch. A more tightly stretched string vibrates more quickly than a loose string, which is why the pitch of a string can be adjusted up or down with the tuning peg.
Pitch can be also be adjusted by altering the length of the string–which is what the player does by pushing the strings against the guitar’s neck with his fingers. He’s preventing part of the string from vibrating, effectively shortening the string. A short string vibrates faster than a long string and therefore has a higher pitch.
The volume of a sound is determined by how much air is set vibrating. A tight guitar string simply strung in empty air would make a musical note, but it would be very soft, because its vibrations couldn’t affect very much air. That’s where the hollow body of the guitar comes in. The strings are stretched over a bridge, connected to the “sound board,” the guitar’s belly, usually made of spruce. Through the bridge, the vibrating strings set the sound board vibrating, which, being larger, is able to vibrate a lot more air, especially the air inside the guitar’s hollow body. Those vibrations are released and directed through the hole in the sound board, toward the listener.
Of course, there’s another way to amplify the sound of a guitar strings: electricity. The original electric guitars, appearing in the ’20s and ’30s, were acoustic guitars with an electronic pick-up added. Since the mid-’50s, there have also been solid-body electric guitars, which rely entirely on electrical amplification. A pick-up on the guitar sends a tiny current, corresponding in frequency to the vibrations of the strings, to an amplifier. Inside the amplifier, that current is boosted, then used to vibrate a large speaker, which, again, can set a lot more air vibrating than can the strings themselves, or, for that matter, a spruce sound board. Plus, of course, once you’ve turned the vibration into electricity, you can change it around, producing sounds that bear only a passing resemblance to those we associate with non-electric guitars.
Many factors are involved in making a guitar sound like a guitar. The sound starts with an attack–the sudden sound of the finger or pick plucking the string–followed by a decay as the string’s vibration slowly dies away. An important part of the decay are what are called harmonics. The plucked string vibrates simultaneously as a whole and in equal parts: halves, thirds, fourths, etc. The pitch is determined by the vibration of the whole, but mixed in with it are faint, higher pitches from these vibrating partial segments. Sometimes the guitar player uses these for effect: by lightly touching the vibrating string, it’s possible to cancel out the full-length vibration and hear only the higher pitches produced by the vibrating segments.
Complicated things, guitars, as you can see. Fortunately, you don’t have to know all this stuff to learn to successfully play them.
I just hope it helps.
