音質評価のための7属性

抄録

As a result of determining a macroscopic structure of tone quality by sensory evaluations and multidimensional scaling method, it seemed that the psychological space applicable to tonal descriptive terms is composed of three main attributes, namely LOUDNESS(loud-sorf), PITCH(high pitched-low pitched) and PLEASANTNESS(pleasant-unpleasant) mutually almost orthogonal. Moreover, four sub-attributes intersecting obliquely to the three main-attributes were found. These sub-attributes included CONSONANCE (clear-turbid), BRIGHTNESS(bright-somber), RICHNESS (rich-thin) and SMOOTHNESS (smooth-rough). As a matter of fact, these four sub-attributes depend on the three main-attributes(Fig. 10). For example, the "clear" quality of consonance is "soft", "high pitched" and "pleasant" sound, while the "turbid" quality is "loud", "low pitched" and "unpleasant" sound, and this result thoroughly corresponds to the CONSONANCE THEORY. The tonal sources used for the present hearing experiments consist of four groups. They are (1) 57 synthetic tones the physical values of which are distinctly grasped, (2) 97 musical instrument solo tones, (3) 44 tones by varying a part of the sound of "Scheherazade", which is the orchestral music with dominant string sections, and (4) 33 tones by varying a part of "Pictures at an exhibition", which is the orchestral music with dominant percussion and brass sections. As for the variation of above mentioned two orchestral sources, the quantitative variations such as spectrum form, intensity, phase modulation and echo were given, 41-53 hearing panels evaluated these tones by the choise of 38 tonal descriptive terms(Table 1) in the auditorium. For analysis, the program by Kruskal was used. (Fig. 4). As the result of this analysis, configurations in Fig. 6〜9 were obtained in three dimensions for each two source groups(Table 3). As for the distribution of the terms for these four source groups, the words of praise and displeasure distributed in two semispherical shell space divided by LOUDNESS-PITCH plane. At the center of the two hemispheric configurations, "pleasant" and "unpleasant" distributed, which represent important factors. This axis was stable even if the sources are different, therefore, PLEASANTNESS is regarded as the third main attribute following LOUDNESS and PITCH(Table 4). Next, the stable terms distributing in the diagonal quadrants among eight quadrants in Fig. 6〜9 are closely examined in common in four source groups, then the terms of four sub-attributes described above were extracted. When the above experimental data were reanalyzed with 14 terms concerning three main attributes and four sub-attributes, the stress in three dimensions decreased further, and approximately similar configuration was obtained. Based on these facts, it is suggested that the fourteen tonal descriptive terms concerning three main-attributes and four sub-attributes are sufficient for deriving the macroscopic structure of tonal sources.