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1.2: Elements of Sound

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    51172
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    From the perspective of a musician, anything that is capable of producing sound is a potential instrument for musical exploitation. What we perceive as sound are vibrations (sound waves) traveling through a medium (usually air) that are captured by the ear and converted into electrochemical signals that are sent to the brain to be processed.

    Since sound is a wave, it has all of the properties attributed to any wave, and these attributes are the four elements that define any and all sounds. They are the frequency, amplitude, wave form and duration, or in musical terms, pitch, dynamic, timbre (tone color), and duration.

    Definitions: Element Musical Terms
    1. Frequency Pitch How high or low
    2. Amplitude Dynamic How loud or soft
    3. Wave form Timbre Unique tone color of each instrument
    4. Duration Duration How long or short

    Frequency

    The frequency, or pitch, is the element of sound that we are best able to hear. We are mesmerized when a singer reaches a particularly high note at the climax of a song, just as we are when a dancer makes a spectacularly difficult leap. We feel very low notes (low pitches) in a physical way as well, sometimes expressing dark or somber sentiments as in music by country singers like Johnny Cash, and other times as the rhythmic propulsion of low-frequency pulsations in electronically amplified dance music.

    The ability to distinguish pitch varies from person to person, just as different people are better and less capable at distinguishing different colors (light frequency). Those who are especially gifted recognizing specific pitches are said to have “perfect pitch.” On the other hand, just as there are those who have difficulty seeing the difference in colors that are near each other in the light spectrum (color-blind), there are people who have trouble identifying pitches that are close to each other. If you consider yourself to be such a “tone-deaf” person, do not fret. The great American composer Charles Ives considered the singing of the tone-deaf caretaker at his church to be some of the most genuine and expressive music he experienced.

    An audio compact disc is able to record sound waves that vibrate as slow as 20 times per second (20 Hertz = 20 Hz) and as fast as 20,000 times per second (20,000 Hertz = 20 kiloHertz = 20 kHz). Humans are able to perceive sounds from approximately 20 Hz to 15 kHz, depending on age, gender, and noise in the environment. Many animals are able to perceive sounds much higher in pitch.

    When musicians talk about being “in tune” and “out of tune,” they are talking about pitch, but more specifically, about the relationship of one pitch to another. In music we often have a succession of pitches, which we call a melody, and also play two or more pitches at the same time, which we call harmony. In both cases, we are conscious of the mathematical distance between the pitches as they follow each other horizontally (melody) and vertically (harmony). The simpler the mathematical relationship between the two pitches, the more consonant it sounds and the easier it is to hear if the notes are in tune.

    The simplest relationship of one pitch to another is called the octave. The octave is so fundamental that we give two pitches an octave apart the same letter name. The ratio between notes an octave apart is 2:1. If we have a note vibrating at 400 Hz, the pitch an octave higher vibrates at 800 Hz (2 * 400 Hz). The pitch an octave lower than 400 Hz has a frequency of 200 Hz (400 Hz / 2).

    Screenshot (429).png

    Example 1.1 Example 1.2

    Example 1.1 Two sound waves one octave apart. The bottom is 1/400th of a second of a sine wave vibrating at 400 Hz.

    Example 1.2 Two sound waves with the same frequency, the top is 10 db softer than the bottom.

    Amplitude

    Amplitude is the amount of energy contained in the sound wave and is perceived as being either loud or soft. Amplitude is measured in decibels, but our perception of loud and soft changes depending on the sounds around us. Walking down a busy street at noon where the noise in the environment might average 50 decibels, we would find it difficult to hear the voice of a person next to us speaking at 40 decibels. On that same street at night that 40 decibel speaking voice will seem like a shout when the surrounding noise is only about 30 decibels.

    Wave Form

    The wave form of a sound determines the tone color, or timbre that we hear and is how we can tell the difference between the sound produced by a voice, a guitar, and a saxophone even if they are playing the same frequency at the same amplitude.

    The simplest wave form is the sine wave, which we have seen diagrammed in the examples for frequency and amplitude above. Pure sine waves rarely occur in nature but they can easily be created through electronic means. An instrument with a timbre close to the purity of a sine wave is the flute. The violin section of the orchestra, by contrast, has a much more complex timbre as seen in its wave form below.

    Screenshot (434).png

    Example 1.3 Example 1.4

    Example 1.3 Wave form of a solo flute.

    Example 1.4 Wave form of a violin string section.

    Duration

    Every sound event has its unique duration, which we perceive as being either short or long, depending on the context. Several durations, one after another, create the rhythm of a piece.


    This page titled 1.2: Elements of Sound is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Douglas Cohen (Brooklyn College Library and Academic IT) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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