Voice classification in non-classical music the muscular, aerodynamic, and acoustical conditions in the larynx and in the vocal tract. The subglottal pressure, the driving force in phonation, needs to be adapted in accordance with the laryngeal conditions.” In other words, the very act of singing consistently within one technique or another literally causes the voice to physically develop in different ways, and thus change the timbre of that particular voice. Another example would be a coloratura soprano in opera. This is not only the highest female voice in opera, but also distinguished by its ability to do vocal acrobatic leaps, fast vocal runs and trills,
The Singing Voice of Japan choir organ "Utagoe" (June 1949) in these terms: However, even after the first issue of the choir organ, the script for the Japanese word "Utagoe" in Kanji (歌声) and one mixed with Hiragana (歌ごえ) were sometimes used by authors of books or periodicals concerning The Singing Voice of Japan, while an exclusive formalization of Hiragana script (うたごえ) has never been imposed by any official organization of the movement. A very remarkable example of the graphical oscillation would be the autograph of Akiko Seki dedicated to the national Festival of December 1962, in which she wrote one of the movement slogans