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The viola (;〔Only the pronunciation () is used in US English, as shown by the entries in the (American Heritage Dictionary ) and the (Merriam-Webster Online Dictionary ), but both this pronunciation and () are used in UK English, as shown by the entries in the (Cambridge Advanced Learner's Dictionary ) and the (Oxford Dictionaries ). Compare with the US and UK pronunciations of the flower called ''viola''.〕 (:ˈvjɔːla)) is a bowed string instrument. It is slightly larger than a violin in size and has a lower and deeper sound than a violin. Since the 18th century it has been the middle voice of the violin family, between the violin (which is tuned a perfect fifth above it) and the cello (which is tuned an octave below it).〔Until the end of the 17th century there was the tenor violin, tuned a perfect fourth below the viola.〕 Music that is written for the viola differs from that of most other instruments, in that it primarily uses the alto clef, which is otherwise rarely used. Viola music employs the treble clef when there are substantial sections of music written in a higher register. The viola occasionally has a major role in orchestral music. In the earlier part of the 20th century, more composers began to write for the viola, encouraged by the emergence of specialized soloists such as Lionel Tertis. Englishmen Arthur Bliss, York Bowen, Benjamin Dale, and Ralph Vaughan Williams all wrote chamber and concert works for Tertis. William Walton, Bohuslav Martinů and Béla Bartók wrote well-known viola concertos. Paul Hindemith wrote a substantial amount of music for viola. In the latter part of the 20th century a substantial repertoire was produced for the viola. == Form == The viola is similar in material and construction to the violin. A full-size viola's body is between and longer than the body of a full-size violin (i.e., between ), with an average length of . Small violas typically made for children typically start at , which is equivalent to a half-size violin. For a child who needs a smaller size, a fractional-sized violin is often strung with the strings of a viola. Unlike the violin, the viola does not have a standard full size. The body of a viola would need to measure about long to match the acoustics of a violin, making it impractical to play in the same manner as the violin. For centuries, viola makers have experimented with the size and shape of the viola, often adjusting the proportions or shape to make a lighter instrument with shorter string lengths, but which still has a large enough sound box to create an unmistakable "viola sound". Experiments have tended to increase the size of the viola, in the interest of improving the instrument's sound. Hermann Ritter's ''viola alta'', which measured about , was intended for use in Wagner's operas. The Tertis model viola, which has wider bouts and deeper ribs to promote a better tone, is another slightly "nonstandard" shape that allows the player to use a larger instrument. Many experiments with the acoustics of a viola, particularly increasing the size of the body, have resulted in a much deeper tone, making it resemble the tone of a 'cello. Since many composers wrote for a traditional-sized viola, particularly in orchestral music, changes in the tone of a viola can have unintended consequences upon the balance in ensembles. More recent (and more radically shaped) innovations have addressed the ergonomic problems associated with playing the viola by making it shorter and lighter, while finding ways to keep the traditional sound. These include the Otto Erdesz "cutaway" viola, which has one shoulder cut out to make shifting easier; the "Oak Leaf" viola, which has two extra bouts; viol-shaped violas such as Joseph Curtin's "Evia" model, which also utilizes a moveable neck and a maple-veneered carbon fibre back, to reduce weight: violas played in the same manner as cellos (see vertical viola); and the eye-catching "Dalí-esque" shapes of both Bernard Sabatier's violas in fractional sizes—which appear to have melted—and David Rivinus' ''Pellegrina'' model violas. Other experiments that deal with the "ergonomics vs. sound" problem have appeared. The American composer Harry Partch fitted a viola with a cello neck to allow the use of his 43-tone scale. Luthiers have also created five-stringed violas, which allow a greater playing range. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「viola」の詳細全文を読む スポンサード リンク
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