The sound quality of concert halls and opera houses

Author: Binaural Author: Wang Jiqing et al / Country: United States / United States
Publisher:
Publishing Time: 2002-08-01
Features: [Excerpt:] Since the 1880s, the number of concerts has been increasing, becoming a routine habit for Europeans and Americans, and later for the Japanese. In the 1920s, attending concerts was very common in the United States. Over the next two decades, the invention of radio and economic downturns reduced the frequency of concerts. However, after World War II, concerts became even more common. What is striking is the wave of interest in classical music that emerged in Japan. Tokyo, the capital of Japan, quickly became a major concert metropolis in the world, exemplified by the six Japanese halls introduced in this book, along with the emergence of numerous Japanese orchestras, public music schools, and sponsors of concerts. The concert in the 20th century underwent tremendous changes. Many contemporary composers wrote for large orchestras, employing techniques similar to those developed in the second half of the 19th century but incorporating new harmonies, new instruments, and new sound effects. Other works demonstrated a return to the smaller halls and clearer sound of earlier times, requiring smaller ensembles and the direct arrangement of instruments as in earlier days. More inventors experimented with sounds from unconventional sources rather than conventional instruments year after year, using electronic laboratories, tape machines, and computers to create new musical works or at least novel sounds. To accommodate the needs of modern concert halls, halls must be able to host a wide range of music in different styles. The "knowledge-based" transparent concert hall hopes for high clarity, as Bach demanded. Some modern halls have been built to meet this requirement—with a mid-frequency reverberation time of about 1.4 seconds and high clarity. These halls are often referred to as "Hifi" halls. Passionate or sentimental modern music sounds excellent in halls with high fullness and low clarity. However, the practical solution for a hall to accommodate different musical styles is variable acoustics—several halls studied in this book have attempted this. The Meyerson Symphony Center's McDermott Concert Hall in Dallas, Texas, is a notable example of wide-ranging variable acoustics. Subsequent attempts involve using electronic technology to make the hall's acoustics variable—art and technology are gradually gaining acceptance. Perhaps one day, music will no longer be performed in concert halls. Multi-channel recordings with surround sound and wide-screen television will replace the real concert hall. If this day comes, reverberation can be adjusted electronically by the audience from one piece to another. Can you imagine it? Musicians will disappear, along with the concert hall, the symphony orchestra, the concert audience, ushers, and ticket takers! At that time, computers, CDs, or DCDs, and the internet will play a major role!
European (non-Wagner) opera European opera houses, since their design and construction, have become the most stable venues for performing music in the history of music halls. At least since 1700, horseshoe-shaped theaters have been built, surrounded by tiers of boxes and topped with cheap balconies. The 1778-built, beloved La Scala Opera House in Milan, Italy, is a perfect example. Almost every major city in Europe imitated the horseshoe-shaped theater. The tiered circular theater became conventional, limiting opera composers to a single musical style. Opera imposes different acoustic conditions than orchestral music. Singing must be considered a form of communication that is no different from language. Especially in the fast-paced works of Mozart and Rossini, where the tongue struggles to follow, the reverberation time must be shorter to maintain the intelligibility of the lyrics, so that subsequent speech is not obscured by the reverberation of past sounds. Except for Wagner's works, European opera suits halls with acoustics suitable for Baroque period music and chamber music, i.e., halls with high clarity and low fullness. Many opera houses—La Scala in Milan, the Venice Opera House, the San Carlo in Naples, the Garnier in Paris, the Royal Opera in London, the Vienna State Opera, and the Philadelphia Academy of Music—meet these requirements. In these opera houses, the singers' voices are both clear and sufficiently loud to reach the audience, and the orchestral sound is clean and undistorted. The balance between the orchestra and the singers is supported by acoustic design and the conductor's control of the orchestra. In Europe, opera is almost always sung in a language the audience understands. Most opera audiences in Europe emphasize the importance of understanding the lyrics. In the United States (and perhaps soon in Japan), this is different. Opera is rarely sung in the local language, and audiences often have to rely on subtitles to understand the lyrics. An American audience, Eliot Klein, said: "People go to the opera to hear music. Most either don't understand the language used in opera or visit the opera more like watching a play. It doesn't matter whether the reverberation makes the lyrics unclear or masks them. In my opinion, only music should determine the reverberation in an opera house." Therefore, it seems that opera in other places could be performed in theaters with longer reverberation times than those in Europe. The Metropolitan Opera in New York is an example, with a mid-frequency reverberation time of about 1.7 seconds.
Wagner's opera Wagner broke the traditional style of Baroque opera and developed a completely personal but still within the Romantic tradition. From his pen flowed several extraordinary and exciting operas—what he called "music dramas." Wagner's romantic music is best supported by high fullness and low clarity. To achieve the best acoustic environment for his musical style, Wagner designed his own opera house—the Bayreuth Festspielhaus in Germany, which is a theater that perfectly combines a longer mid-frequency reverberation time of about 1.6 seconds with a fully integrated orchestra. Although Wagner used a large orchestra (100 to 130 instruments), the appropriate balance between singers and the orchestra was maintained by the orchestra pit, which was sunk into the ground and covered, adding a mystical touch to the music. Wagner's orchestral music is slower, and the sound is excellent in a theater with a mid-frequency reverberation time of about 2 seconds. However, for the lyrics to be intelligible, the reverberation time should be slightly shorter, around 1.6 seconds at Bayreuth. If the ratio of early sound energy to reverberation sound energy was higher earlier, a reverberation time of up to 1.8 seconds might also be acceptable.
Marshall and Baran's research Marshall studied the cross-sectional shapes of concert halls in 1967–1968 and their effects on the energy and time distribution of early reflections. He hypothesized that people prefer narrow rather than wide rectangular halls because narrow halls provide stronger and more lateral reflections reaching their ears. Marshall later (1979) concluded that lateral reflections give listeners a sense of being surrounded by sound. This sense of being surrounded is also called "spatial perception," which increases with higher sound levels; spatial perception is described as the feeling of being fully or partially surrounded by sound, as opposed to being outside the sound, like listening through a window. He proposed that the ratio of lateral reflection energy to total sound energy could serve as a measure of spatial perception. Baran, working with Marshall in 1981, confirmed and extended these findings. Two different measures were used to compare the effects of lateral reflections: (1) the ratio of the output of an 8-shaped directional microphone (which automatically eliminates sound energy arriving at the measurement position, whether direct sound or reflected sound from the ceiling and overhead panels) in the first 80 ms after direct sound to the output of a five-directional microphone. This measure is called the "lateral sound energy percentage" (LF); (2) IACC, measured based on the outputs of two microphones placed in or simulating the ears of a human head. Recently (1995), Tagawa, Binaural, and Okano demonstrated that IACC is a more accurate measure of spatial perception. This was something Marshall had long been interested in.
Ando's research In 1985, Ando exposed young listeners to sound fields generated by electronic methods, broadcasting several symphonic pieces at different rates. His experimental sound fields simulated those in concert halls, including direct sound, reflections from different directions with varying intensities, and reverberation with different times. Using paired-comparison experiments, Ando discovered four statistically independent subjective parameters important for acoustic quality from the listeners' responses: (1) loudness (denoted as G); (2) intimacy (denoted as t1); (3) reverberation (denoted as RT); and (4) interaural cross-correlation (denoted as IACC). Ando also derived a scoring method that combined the four acoustic attributes into a single evaluation number. However, this method is too complex and still needs to be applied in concert hall design to prove its value. Ando's data indicate that listeners prefer shorter initial delay gaps when listening to active music, around 30 ms. If the energy of the subsequent reverberation field is sufficient, they also prefer shorter initial delay gaps, also around 30 ms. Ando also proposed that "listeners generally prefer sounds with more acoustic information in early reflections." These results are consistent with Binaural's findings in 1962, but Ando's scoring method is entirely different, and Binaural's preferred delay gap is slightly shorter. Ando also found that some listeners prefer weaker reverberation, while others prefer higher clarity.