ASA/CAA '05 Meeting, Vancouver, BC
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Music Halls from the 18th to 20th Centuries:
Changes in Acoustical and Architectural Criteria
Youngmin Kwon- firstname.lastname@example.org
Architectural Technology Research Center, School of Architecture
University of Florida
231 Arch PO BOX 115702
Gainesville, FL 32611
Popular version of paper 5aAA2
Presented Friday morning, May 20, 2005
Joint ASA/CAA Meeting, Vancouver, BC
This research identified the changes in architectural and acoustical criteria
in halls for music performance built in the 18th through 20th centuries. The
study involved seventy-one halls, including fifty- nine concert halls and twelve
multi-purpose halls. The halls were classified in five specific periods on the
basis of chronology in music and architectural acoustics: Classical period (1750-1820),
Romantic period (1821-1900), Pre-modern period (1901-1950), Modern I (1951-1980),
and Modern II (1981-2000). Architectural and acoustical criteria found mostly
in Beranek (2003 & 1996) were chronologically surveyed and tabulated, and relationships
among these criteria were further investigated to identify trends in architectural
and acoustical design for each of the chronological periods identified.
CHRONOLOGICAL PHASES IN ROOM GEOMETRICAL CRITERIA
The halls were categorized in five primary room shapes: shoebox, fan-shape,
horseshoe, arena/semi-arena, and irregular style. The shoebox style was found
as a general room shape for music performances in all time periods. A number
of the shoebox style halls were observed in all periods except the Pre-modern
period. The fan-shape style was developed during the Pre-modern period and became
a primary room shape in the 20th century. Another trend found in this study
is that the room shapes of the halls for music have become more diverse since
the latter half of the 20th century. The use of arena or semi-arena style has
gradually increased during the Modern I and Modern II periods, and irregular
styles in room shape have often been observed in these periods.
Seating Capacity, Room Volume and Room Volume per Seat
The average seating capacity and room volume had increased through the Pre-modern
and Modern I periods from approximately 2,070 to 2,470 seats and from 572,000
to 760,000 cu. ft. respectively. It seems that this tendency is relevant to
the increase in number of large scale fan-shape halls built during these periods.
The average seating capacity of the fan-shape halls (15 halls total) reaches
about 2,580 people, which is larger than both the overall average of 71 halls
and the average of shoebox halls (24 halls total) by approximately 330 and 550
seats respectively. Then, the seating capacity decreased abruptly by about 400
seats during the Modern II period, while the room volume was maintained or decreased
slightly. This resulted in an increase of room volume per seat. Interestingly,
during the Modern II period, the average seating capacity has come close to
the average of 24 shoebox halls, which is about 2,030 seating.
The average room dimensions of width and length had increased until the Modern
I period and have decreased since then, while the average ceiling height has
marginally increased to approximately 60 ft, which is the overall average of
71 halls. The tendency in either width or length observed until the Modern I
period seems to be again primarily owing to the increase in number of large
scale fan-shape halls. In fact, the average values of width and length obtained
in the fan-shape halls are larger by about 20 ft and 8 ft respectively in comparison
to the overall average values obtained in 71 halls total. Another interesting
note is that the chronological trend in room volume was found to have a closer
relationship particularly with the one in room width. The statistical correlation
coefficient of adjusted R-square between these two variables was 0.705.
CHRONOLOGICAL PHASES IN BALCONY OVERHANG CRITERIA
Number of Rear Balcony Overhangs
Over the past two centuries, there have not been significant changes in the
average number of rear balcony overhangs. It was found that the 71 halls studied
in this paper have in general two balcony overhangs at the rear of the room.
The average number of rear balcony overhangs in a hall seems to be greatly influenced
by its room shape. As shown in Figure 2 (b), the arena style halls were
found to hold usually one overhang at the back, while the horseshoe style halls
hold usually three overhangs. There are one or two overhangs found in the fan-shape
halls. For example, the average number of rear balcony overhangs in the Modern
I period marks below the overall average of 1.8 (see Figure 2 (a)). This
was resulted from the fact that there were many fan-shape or arena style halls
(11 halls out of 23 halls), which have fewer overhangs, but there were no horseshoe
style halls found in this period.
D, H, D/H Ratio and Vertical Angle of View θ
Note that the following discussion is related to the first rear balcony overhang.
Over the last two centuries, it was found that there have not been significant
changes in average overhang opening height (H). The overall average H of the
overhangs from 71 halls is 12.6 ft. However, there have been remarkable changes
in average D/H ratio along with remarkable changes in average overhang depth
(D). The values of these two elements - average D and D/H ratio - had increased
to a great degree until the early 20th century, and have noticeably decreased
since then. For example, the D/H ratio increased from 1.47 to 2.45 for the halls
constructed during the Pre-modern period and has decreased to 1.36 for the halls
opened in the Modern II period. The trend in vertical angle of view (θ) was
drawn contrary to the trend observed in D or D/H ratio above. The audience seated
at the deepest row under the balcony in a hall constructed during the Pre-modern
period was exposed to a quite narrow vertical view angle of approximately 22
degrees. The average θ has increased to about 33 degrees as the D and D/H ratio
has decreased since then.
CHRONOLOGICAL PHASES IN ACOUSTICAL CRITERIA
Based on quantitative analyses of room acoustical criteria over chronological
periods, it was found that overall acoustical quality is relatively poor in
the early 20th century (Pre-modern period) while relatively better in Romantic
period. This acoustical quality in the Romantic period was able to be substantiated
in the hall with rather an intimate room volume (about 572,000 cu. ft in average)
and a lower seating capacity (about 2,070 seats in average) compared to other
periods. On the contrary, both occupied and unoccupied reverberation times (RT),
early decay time (EDT), and clarity index (C80) were particularly poor in the
Pre-modern period. This feature in acoustical quality seems to be related to
the increase in number of fan-shape halls during this period. In fact, acoustical
quality figured in the fan-shape halls was observed quantitatively poor for
most of the acoustical criteria including both occupied and unoccupied RT's,
EDT, C80, sound strength or loudness index (G), and lateral energy index (LF).
RT, EDT, G and C80
The average values both in RT and EDT had decreased from the 19th century through
the Pre-modern period and then have gradually increased. The average value of
C80 has gradually decreased through the 20th century. The average G value had
decreased from the 19th century through Modern I period and then has increased
Correlation between Acoustical Criteria and Room Volume per Seat
Figure 3 compares the contour of room volume per seat with the contours
of RT and C80 over chronological periods. Statistical analysis on this comparison
showed that these variables are closely relevant to each other. The statistical
correlation coefficient of adjusted R-square scores 0.576 between the
room volume per seat and the occupied RT. In addition, it was found that the
C80 is negatively correlated with the room volume per seat. The adjusted
R-square between these two variables marks -0.473.
Figure 3. Chronological Comparison of Trend in Room Volume/Seat with
Trends in RT (Occupied) and C80 (a) Room Volume per Seat, (b) Occupied RT, (c)
To summarize trends observed in the past two decade modern period (1981-2000),
the seating capacity as well as the room dimensions of width and length tended
to decrease but the room volume remained relatively constant. This resulted
in a larger room volume per seat. A hall usually has two balcony overhangs at
the back. The average D and D/H ratio of the first rear balcony overhangs tended
to be lower. Lastly, acoustical quality has in general improved through the
latter half of the 20th century. The average occupied reverberation time obtained
in the past two decades reached 1.94 seconds, which is the highest value in
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