ESSENTIALS of Classical Music
WHAT IS A MUSICAL TONE?
All sound consists of air moving in a particular way. (Technically, sound can be conveyed by water as well—you can hear sounds while you scuba dive, but they don’t sound the same as in the air.) A musical sound consists of a regular pattern of vibrations; what we term a “noise” usually is the result of irregular sound patterns. Acoustic musical instruments produce these vibrations by means of a moving wire (“stringed” instruments), a column of air (“wind” instruments) or a moving membrane or surface (“percussion” instruments, as well as the ultimate musical instrument, the human voice).The 1979 movie Alien was famously promoted with the tagline, “In space, no one can hear you scream.” It’s true; there is no sound in a total vacuum. It’s one bit of realism not accepted in the conventions of most outer-space movies, like the Star Wars series, in which rockets taking off in space roar and whoosh and explosions give off mighty bangs. George Lucas admitted it was contrary to fact to have such sound effects, but felt audiences could not relate to action/adventure sequences without the impact of sound. Compare his space-chase sequences to the eerie rescue scene in Stanley Kubrick’s 2001: A Space Odyssey, in which Keir Dullea could hear only his own breathing as he pursued his friend’s body.
Ignoring, for convenience’s sake, the avant-garde experiments of such philosophically motivated composers as John Cage, for whom anything could be music—even silence or random noise—we’ll find that, broadly speaking, a musical tone possesses specific characteristics. It is these characteristics that enable you to tell, just by listening, whether you are hearing a violin or an oboe. These characteristics are:
Most musical tones have a single, specific pitch, that is the quality of how “high” or “low” the note is, which is indicated in a musical score by the position of the note on the staff and can be measured in vibrations per second. As a general rule, if you double the vibration rate of any given note, you get the same note one octave higher. Our ears hear these “octave equivalents” as essentially the same note. A man and a woman singing the same melody at the same time usually are singing in octaves, because of their different vocal ranges, but we have no difficulty hearing that they are singing the same tune. If two instruments play a note with the identical rate of vibration, it is called a unison.
Unpitched sounds used in music are found in the percussion section of an orchestra: the bass drum, cymbals, tambourine and snare drum, to name a few. Not all drums are unpitched, however; the timpani (kettle-drums) are tuned to specific pitches—in fact, modern timpani are equipped with pedals that enable the player to change the pitch with one simple movement. Back in 1837, when Hector Berlioz composed his mammoth Requiem, he called for a gigantic orchestra with 16 timpani; today, thanks to the use of pedals, it can be performed with only four.
This is indicated in a score by a variety of markings, called dynamics, usually involving the letters p (for piano, or soft) and f (for forte, or loud). [This is the origin of the name for the piano. Created by Bartolommeo Cristofori around 1700, it was originally called “gravicembalo col piano e forte,” in other words, a great keyboard that could play soft and loud. Prior to that time, keyboard instruments created sound by plucking the string, which did not allow for variations of loudness. Cristofori’s new instrument struck the string with a hammer, and the amount of force used by the player determined how loud the note would sound. The instrument’s name was shortened first to “pianoforte” and later to simply “piano.” Nowadays, early pianos or replicas thereof are often referred to as “fortepianos” to distinguish them from the modern variety.]
In most instances, the dynamic range runs from ppp (pianissimo, extremely soft) to fff (fortissimo, extremely loud), although some composers toward the end of the 19th century started to push the envelope, so to speak, by going as far as ffff and even fffff. At the other end of the spectrum, Verdi used ppppp in his 1874 Requiem; and Tchaikovsky, not to be outdone, indicated pppppp in his Symphony No. 6 of 1893.
This refers to the quality of a sustained note as determined by the particular overtones a tone comprises. A note without any overtones, such as a tone generated by a synthesizer, is very flat and eerie-sounding; used exclusively, such tones would become either extremely boring or, worse, extremely grating.
To get a concept of overtones (or partials or harmonics, as they are sometimes called), think of a single vibrating string. Under normal conditions, the string vibrates at a particular rate, called the fundamental, which determines its pitch. But as it vibrates freely, it also subdivides itself into halves, thirds, fourths, etc., each subdivision producing a very faint note higher than the fundamental. For example, a string vibrating at one pitch will also produce a tone one octave higher, then a perfect fifth above that, a perfect fourth above that, a major third above that, a minor third above that, and so on. All of these tones are present in theory; in reality, the physical design of an instrument will determine which overtones are present and how prominent they are. The various arrangements of overtones in any instance are largely what give each instrument its distinct sound quality. This is further complicated by each note’s “envelope.”
Like a good short story, a note has a beginning, a middle and an end. The “middle” portion is usually relatively consistent in quality, but in order to get the air vibrating in that particular way, the instrument starts off with an “attack” (the beginning) and eventually ends with a “release.” These elements of the tone may have characteristics completely different from the main portion of the tone itself, sometimes even being a percussive noise. If you pluck a string, it will have not only its distinctive timbre, but also the sound of the plucking itself, which briefly distorts the string to get it moving. Similarly, to stop a vibrating string, such as when you release a piano key, a damper hits the string, again modifying the sound for a brief instant. Since we are dealing with the physical world here and not a hypothetically ideal state, musical tones may also “decay” as they sound—for example, a vibrating string will eventually lose energy (unless it is reinforced by continued bowing), growing fainter and fainter until it either decays completely (“dies away,” as we would say) or is dampened for a sudden end.
It is the complexity of all these characteristics that made it so difficult for early synthesizers to create truly convincing reproductions of acoustic sounds—a synthesizer may be able to reproduce a note’s pitch and timbre perfectly, for example, but will have much more difficulty reproducing its attack, decay and release. The newer generation of electronic instruments has come close to solving that problem by the use of “sampling,” that is to say the sound is generated by a recording of an actual instrument instead of creating the sound electronically from scratch. The resulting effect of a performance generated by such a device is virtually indistinguishable from a recording of a performance on an acoustic instrument; whether it is indistinguishable from a live performance on an acoustic instrument is more open to debate.
If you start to consider the limitless possibilities of sound when you combine more than one instrument, you can begin to appreciate the infinite variety of orchestral sonorities. Ravinia Festival is proud to feature one of the great orchestras of the world—the Chicago Symphony. Their annual summer residence at Ravinia provides a perfect opportunity to discover exactly what astonishing sounds acoustic instruments are capable of producing.