Published
in June 2006
Acoustic Compromises
By Russ Cooper
Not an option for multi-use halls.
Until recently, Amarillo, a city
of 230,000, was served by one multi-use performance hall:
the Amarillo Civic Center Auditorium, in the city’s
Convention Center. With all of its 2324 seats on one level,
the proscenium-style auditorium was not a very inviting
space, nor did it have good acoustics. To be economically
viable, a new hall for the city would require 1200 to 1300
seats and also be multi-use.
However, it was the architect’s
vision to not design the typical multi-use hall with a stage
house that works for theater, musical and opera, but that
is a compromise for music, both acoustically and visually.
Instead, Malcolm Holzman, of Holzman Moss Architecture,
insisted on a “music room first” aesthetic,
with the room adaptable for other uses: theatrically, acoustically
and architecturally.
Home to Three Groups
Opened in January, the Carol Bush
Emeny Performance Hall in Amarillo’s Globe-News Performing
Arts Center is home to three performing groups: The Amarillo
Symphony, The Lone Star Ballet and The Amarillo Opera. Although
the emphasis is on live, unamplified music, Emeny Hall must
accommodate amplified music as well, from rock to pop to
Broadway-style musicals. But this venue is not like other
multi-use halls: It features one of the most unusual acoustical
designs in the world today, developed by Jaffe Holden Acoustics
(JHA) in conjunction with Holzman Moss, with theater design
by Davis Crossfield Associates.
 |
|
The Globe-News Performing
Arts Center in Amarillo TX is home to the Carol Bush
Emeny Performance Hall, which features one of the
most unusual acoustical designs in the world today.
|
Traditional designs of the best
concert halls in the world are one room, rectangular geometries,
“shoe-box” shapes such as Boston Symphony Hall
and the Musikvereinsaal in Vienna. The volume of these rooms
is such that a symphony orchestra at full sforzando energy
levels does not sound loud or harsh.
Acoustically, this means that the
hall must have sufficient volume for the sound of an orchestra
to develop properly, sustain and then decay naturally. The
ideal volume to achieve the preferred great sound in these
traditional concert halls is around 600,000 cubic feet.
Symphony Hall and Musikvereinsaal seat 2650 and 2044, respectively.
To maintain the necessary acoustic volume for a symphony
orchestra to sound great in a hall with a seating count
of 1300 would require an extremely tall space that would
have appeared and felt cavernous.
The design team’s solution
was to use a room-within-a-room concept. The inner room
would provide the architectural boundary of the space, thus
offering the small-theater feel of an intimate and warm,
inviting space. The outer room, which would be coupled acoustically
to the inner room through strategically placed openings,
would provide the extra volume necessary for the proper
acoustics (see Figure 1).
 |
Figure 1. Emeny
Performance Hall Section Acoustical Systems. |
|
 |
Figure 2. The
traditional shell design. |
Traditional vs. ‘Shaper’
Because JHA is experienced in perfecting
orchestra sound on the stage side for a multi-use hall through
its “concert hall shaper” design, it was determined
that we would employ this design for the Globe Center project,
but in a slightly different way. The shaper design uses
a hard cap structure to seal off the upper stage loft area
to keep sound from escaping into this large, absorptive
space full of drapery and lights. This hard cap must then
move out of the way when non-music performances are on stage
using stage line sets.
The traditional approach is to
use a series of portable towers and “tip and fly”
ceiling panels. Setting the stage for orchestra concerts
with this type of shell can take up to an hour with a crew
of three to four people. The three or four ceiling panels
live permanently on heavy counter-weighted or electric winch
line sets that cannot be used for any other purpose.
The width of the stored ceiling
panels “kills” the adjacent line sets as well,
eliminating up to 12 line sets for theatrical use for non-orchestral
programming. The wall towers, although “nestable”
in their design, take up valuable offstage storage space.
Figure 2 illustrates the traditional shell design.
Traditional orchestra shell designs
have acoustical drawbacks:
• If the shell ceiling design is “open”
(the openings between the panels are large), sound is allowed
to escape into the absorptive stage loft.
• If the shell ceiling design is “closed”
(the openings between the panels are minimal), the sound
on stage becomes too loud and harsh.
• The volume of the stage platform is small in comparison
to the rest of the room, which creates two distinctly different
acoustical environments.
 |
Figure 3. (Left) The Pepsico
Recital Hall, Texas Christian University. (Top) The
Bass Hall Ft. Worth TX concert hall shaper.
|
| |
|
Figure 4 illustrates the concert
hall shaper deployed in Bass Hall.
|
Problem Solver
The “concert hall shaper”
solves all the acoustical as well as theatrical difficulties
of the traditional design. Here’s how it works: The
stage house structure, by nature, is inherently solid and
hard and rigid, perfect for reflecting all frequencies of
sound! Why not use this nature to our benefit and create
an acoustical volume on stage that couples or matches that
of the house to create more of a one-room hall?
And, why not visually match the
stage platform architecture to the house architecture so
the experience is of being in one room, not the traditional
two-room approach of an audience chamber and then a stage
inside a proscenium?
The “music room first”
aesthetic led to these fresh perspectives, and away from
the acoustical compromises inherent in traditional multi-use
room design.
The overall design of the Globe-News
hall is an evolution of a smaller scale design we developed
for the PepsiCo Recital Hall at Texas Christian University
(Fort Worth TX), where the entire room was a fixed structure
with inner and outer rooms. In this design, adjustable acoustics
control reverberation and openings in the inner room to
the outer room coupled the two spaces acoustically.
Still, the Globe-News Center orchestra
shell differs from concert hall shapers of some of our previous
designs, such as Tokyo International Forum, Bass Hall (Ft.
Worth TX) and Gaylord Hall (Oklahoma City OK) (see Figure
3).
The hard cap to close off the absorptive
stage house in these designs was an element that moved into
position from an upstage location and had separate wall
towers that stagehands moved into place from an offstage
storage location. The shaper in both Bass Hall and Gaylord
Hall required the stage to be struck, and the ceiling was
lifted up from winch points on the downstage edge (see Figure
4).
Single Unit Construction
The Globe-News shell is a single
unit construction consisting of an industrial materials
mover, rolling gantry crane from which the shell hard cap
is suspended, and lower ceiling and walls as well. The hard
cap ceiling is attached to the top side of the truss between
the cranes and consists of a thick plywood layer. The lower,
articulated shell consists of thick MDO plywood with a finish
stain constructed in three segmented arches with openings
in between each segment (see Figure 5). This is the same
material used in the inner room of the audience chamber.
 |
| Figure 6. The room-within-a-room. |
The entire assembly lives in an
upstage garage. Instead of taking a crew of three or four
up to an hour, moving the shell into place becomes a motorized
operation managed with a handheld remote as small as an
iPod and takes just two to four minutes.
The shell is also a room within
a room (see Figure 6). The inner wood shell has openings
at the gaps between the three arches to the outer room that
is bordered by the hard cap shaper ceiling and the side
walls of the side stage wings. The cap ceiling intersects
the concrete fly galleries over the side wings, thus completing
the acoustically reflective outer room.
The inner room, both in the stage
and in the house, reflects mid- and high-frequency sound.
More of the low-frequency energy is allowed to pass through
to the outer room where it is reflected back into the house
later, without too much loss in energy, to create a low-frequency
balance of sound often referred to as “warmth”
(see Figure 7).
The outer room in the house has
adjustable acoustic systems to tune the sound of the various
ensembles and to dampen the hall for amplified programming.
The adjustable systems consist of mid- and high-frequency
absorptive velour curtains and mid- to low-frequency absorptive
fiberglass sliding panels, as illustrated in Figure 8 and
Figure 9. When the panels are compacted, this system is
fully reflective; when the panel is opened, the system is
fully absorptive.
Tuning the Room
The measured reverberation times
with various adjustable acoustic systems are shown in Figure
10. For classical symphonic programming, reverberation time
can be as high as 2.5 seconds unoccupied and 2.2 seconds
with full audience. For amplified programming, with the
adjustable acoustic systems in place, reverberation time
is lowered to 1.4 seconds occupied. The shape of the reverberation
time curves shows a flattening out in the low-frequency
region when the adjustable acoustic systems are in place,
allowing for better room control and a tight bass sound
for amplified pop performances.
The pre-opening acoustic check
of the hall included a week-long effort by JHA staff to
tune the room for various ensembles. This meant attending
rehearsals of various groups such as the Amarillo Symphony,
Civic Choral Society, local pop groups, opera singers, the
Harrington String Quartet, etc.
We listened from various seats
in the hall and worked with the music directors to get a
sense of how the music sounded in the hall. We then used
the adjustable acoustic systems to either dampen the sound
or liven it, depending on the need. We also determined the
best onstage location for the performers. Opera singers
in particular want to find the stage “sweet spot.”
Figure 7. Sound propagation in the
hall.
First Event With People
During the tuning, the Globe-News
Center took the opportunity to invite more than 500 local
university and high school students to attend a presentation
I gave on the acoustics of the hall. (This actually was
the first event with people in the hall. It was a great
success and fun as well). The presentation’s tie-in
with the Globe-News Gilliland Education Center, although
not explicit, made perfect sense. The Education Center is
a rehearsal hall, acoustically isolated from the rest of
the facility, that can accommodate the Amarillo Orchestra
and serve as a classroom for distance learning, as well.
The tuning week culminated in a
hard-hat full-house concert for the construction workers
and their spouses, donors, founders and design team members.
Jaffe Holden prepared this event, emceeing and orchestrating
the on-stage appearances by those artists who had helped
us tune the room during the week, this time demonstrating
the flexibility of the hall with the different adjustable
acoustic systems in place. When the shell was moved into
place, and the audience was advised that it was the only
one of its kind in the world and made entirely in the state
of Texas, they erupted into sustained applause.
The acoustic success of the Globe-News
Center hall is borne out by reviews of the first Amarillo
Symphony concert, in which music critic Chip Chandler stated,
“The first true highlight of the concert came with
Copland’s Fanfare, featuring only the orchestra’s
brass and percussion sections. It’s the kind of piece
you want to enjoy with your eyes closed, letting the sound
wash over you and in the orchestra’s rendition, with
the new acoustic clarity, that’s just what was required.
It was gorgeous, simply gorgeous.”
Creating a multi-use hall with
a “music first” aesthetic is a viable option
for new performing arts centers. The costs and space involved
in the storage of the shell must be balanced against the
savings in operating labor and scenic space-saving potential,
as well as the benefits of a no-compromise music performance
space.
For the city of Amarillo, which
raised the $36 million for the Globe-News Center primarily
from private donations, the effort and expense seems to
have been worth it.
For more information, go to www. jhacoustics.com, www.holzmanmoss.
com,
www.daviscrossfield.com.
Russ Cooper is president of Jaffe
Holden Acoustics, Norwalk CT.
|
