Musical Sound

  August 16, 2021   Read time 3 min
Musical Sound
Sound is created with an instrument by setting up vibrations in a string, a column of air, a skin, or solid matter. String instruments or chordophones are plucked (e.g., guitars), bowed (e.g., violins), or struck (e.g., hammered dulcimers).

The pitch of the note produced depends upon the length, thickness, mass, and tension of the string. To sound a higher note, one can decrease the length, thickness, or mass or increase the tension—or alter all four. For example, the strings of a guitar are the same length and at similar tension, but vary in thickness and mass, and thus each can be tuned to a different pitch. Higher notes can be played by pressing a string to the fingerboard, leaving a shorter length free to vibrate.

Wind instruments or aerophones are played by blowing in various ways: i) across a hole onto a sharp edge (whistles and flutes); ii) between two flexible blades (double reeds such as oboes and bassoons; iii) between a flexible blade and a rigid mouthpiece (single reeds such as clarinets and saxophones); iv) between buzzing lips acting like reeds (brass instruments such as trumpets and horns—the material of which the instrument is made is irrelevant, and “brass” remains a useful term, more familiar than “lip-reeds”); v) past a flexible blade in a rigid slot (free reeds such as mouth organs and accordions).

The first three types are known as woodwinds and the fourth as brass, and the pitch they produce depends on the length and shape of their bore, which controls their overtones (see Explanations and Definitions). On a brass instrument, these overtones can be played by varying the tension of the lips and the air speed; on a woodwind, the first few can be played in the same way. On many modern brass instruments, the notes between these overtones are played by the use of valves, or on the trombone with a slide, thereby adding extra lengths of tubing and thus lowering the pitch. On woodwind instruments and some brass, the scale starts on the lowest note of this series; as holes are opened, one after the other, the sounding length of the tube shortens, so raising the pitch. When the top hole is reached, all are covered again and the player blows harder, producing the next overtone, and opens the holes in sequence again. With some free reeds, the pitch depends solely on the length and mass of the reed, but others behave like the other woodwinds.

Drums or membranophones have a skin stretched across a frame and can be struck or rubbed. They may have an open frame (frame drums, such as the tambourine), another skin across the bottom of the frame (tubular drums, e.g., a side drum), or have a closed body (kettle drums, e.g., timpani). The shape and material of the frame affect the tone, while the diameter, thickness, mass, and tension of the skin control the pitch. The instruments of solid matter, that is, the idiophones (e.g., xylophone, triangle, cymbal, etc.), can be struck, rubbed, scraped, or plucked. Any shape and any resonant material can be used. The pitch depends on the nature, volume, density, rigidity, mass, size, and shape of the material.

One further word of introduction. We shall use frequently in these pages such phrases as “in our culture” or “in our music.” They are used in place of the meaningless terms “Western music,” “European orchestras,” and so forth. Possible alternatives are “international culture” and “international music,” for “our” music has become international. We cannot talk of “Western” music when “our” sort of music is played worldwide; the Tokyo Philarmonic, for example, is eastern relative to Berlin, but western from Los Angeles. Nor can we legitimately speak of “European” when, for example, since the seventeenth century (even since the sixteenth, south of the Rio Grande), “our” music has been composed and played in the Americas. When saying our, I write as someone brought up in England and trained as a musician first in America and then in England, but it implies no value judgment—all musics are music. It is only because “Western” and “European” are without meaning in this context that we must have available some word to distinguish between “ours” and that of people brought up and trained in different musics from mine.