Psychological Characteristics of Sound: (2) Loudness

The Music Telegraph | Text 2019/12/10 [11:55]

Psychological Characteristics of Sound: (2) Loudness

The Music Telegraph| 입력 : 2019/12/10 [11:55]

 

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Psychological Characteristics of Sound: (2) Loudness

 

Like the relationship between pitch and frequency, the psychological characteristic corresponding to the intensity, which is an approach by the physical characteristics of sound, is the loudness representing the loudness of a sound. This psychoacoustic study proves that the magnitude of the sound is not only dependent on the intensity, which is purely the loudness, but also dependent on the frequency. This concept requires careful explanation because it is not a research that has been identified with music.

 

 

In 1933 Fletcher and Munson published a book on the loudness dependent to frequency and intensity (Harvey Fletcher and W. A., 'Loudness, It’s Definition, Measurement and Calculation',  Journal of the Acoustical Society of America, Oct. 1933, p 83-103). To produce pure tones, they had the same magnitude at the fundamental frequency of 1 kHz, and as the frequency decreased, the amplitude needed to be smaller. The subsequent curve, the Equal-Loudness contours representing the same magnitude, tells us that the loudness needs to produce the same loudness at different levels.

 

▲ The Equal Loudness Contour

Fletcher and Munson are credited with pioneering work in the 1930s to develop equal-loudness curves, contributing significantly to the understanding of the loudness response of the human ear. Sets of equal-loudness contours are still often referred to as Fletcher-Munson curves. 

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The above measurements are by sine wave only and do not mean that they are measured at other loudness levels. In music, there is a unit that indicates the volume of sound. This unit can be  listed according to its loudness, but it is not possible to specify an absolute volume for this unit. In music notation, the loudness is represented by p (piano), f (forte), and ff (fortissimo). Centered on intuitive factors, psychoacoustic researchers created subjects by asking people how loud the scale of sound was. This is called the 'Sone Scale', which was not considered important in today's music. Knowledge of Equal Loudness contours can be applied to compare complex two-tone sounds in real musical situations. If the two complex sounds with different pitches and harmonics are proportionally adjusted according to the 'Equal Loudness contour', the subjective  magnitudes of the two sounds will be the same. This case is an example of how the results of  previous psychoacoustic studies can be used as a positive aspect of real music, although many future studies may have to show the expansion and limitations of the studies more clearly. 

 

 

 

 

 

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