Theatre Design & Technology - Winter 1975 - 26

of both the designs and the productions should be presented for purposes of comparison. The photographs
should be identified by play title, name of designer,
year of graduation, degree granted, and the name of the
supervising artist-teacher. If the design was actually
produced it would be appropriate to note whether it was
a major production or a laboratory project and by whom
it was directed.
Conclusion
Unfortunately few institutions now prepare students
to present a portfolio as complete as those outlined
herein. Nevertheless, this proposal points the direction
to be taken if educational theatre is to adequately prepare designers to work to professional standards, such
as those set by United Scenic Artists of America.
For artist-teachers this proposal represents not only a
method of presenting student work, but also a means of
up-grading standards to more nearly approximate those
recognized and practiced in the professional theatre.
NEWS
Continued from page 6
Minnesota Orchestra, is the country's latest example. For
instance, the auditorium is separated by a one-inch gap
from its own lobby to isolate the performing area from
extraneous and undesirable sound.
During early planning of the facility, the Minnesota
Orchestral Association prepared a "Design Philosophy"
which outlined hall objectives. It said, "Above all, the
building should help achieve that most important goal excellence of acoustics."
Dr. Cyril M. Harris, New York City, who also did the
acoustical design of the Kennedy Center in Washington
and the Metropolitan Opera Hall, was acoustical consultant. He guided all specifications related to acoustics - layout, building materials, seats, carpeting, fixtures, mechanical equipment, etc.
Besides looking for good sound propagation characteristics, designers desired a hall that had a minimum of
extraneous noise. 'We were demanding," stated Dr.
Harris. 'We sought a hall with a Noise Criteria level of
20 throughout. That goal was met or exceeded." (Note:
NC levels are a logarithmic measure combining sound
frequency and amplitude. A typical level for a quiet
new office building is NC 35, roughly 32 times the acoustical power of an NC 20 curve.)
A part of the solution was a one-inch gap, filled with
insulation, which physically separates the concrete and
brick auditorium from the adjoining structure containing the lobby, administrative offices, mechanical rooms
and ancillary services. This supporting structure is made
of glass, steel and aluminum.
"Air moving systems can also present noise problems," Dr. Harris pointed out. 'We did not want to
hear any sound from the air conditioning." To silence
the ventilation equipment, every air supply duct into
the auditorium and every return duct is equipped with
sound traps. Similar units were also installed at each
fan.
The mechanical and electrical engineers - Michaud,
Cooley, Hallberg, Erickson & Associates, Inc., Minneapolis - specified Aircoustat" Air Duct Silencers, pro-

WINTER,1975

duced by Environmental Elements Corporation, Baltimore, a wholly owned subsidiary of Koppers Company,
Inc. A total of 343 units, principally model SR in three,
five and seven foot lengths, were used. They were supplied by the Gorgen Company, Environmental Elements
sound control agent in Minneapolis.
The Aircoustat sound traps are grouped in bundles
measuring up to 7 ft. x 8 ft. and 7 ft. in length. They are
particularly effective in blocking sounds in the low and
middle octave bands, the type of noise present in the air
conditioning system.
Each trap has baffles die stamped from one-piece
sheets of galvanized steel. These baffles are corru gated
in the direction of airflow, formed to a bellmouth entrance and a smooth exponential exit. They are designed
to control noise in the duct and minimize the possibility
of any airflow-generated noise within the silencer.
The desired sound, that of the orchestra on stage, is
dispersed through the quiet auditorium by hundreds of
angled surfaces on the ceiling and walls. The sloping
ceiling and the wall behind the orchestra have random
patterns of intriguing plaster polyhedral shapes. The
other three walls are sheathed with faceted panels of
oak.
The end result is a magnificent acoustical achievement
that is also visually exciting and quite functional. It was
designed to serve concert-going audiences of the future,
rather than reflect old world elegance.
Orchestra Hall was an immediate success with Minneapolis music lovers. The 2543-seat hall attracts capacity
crowds to nearly every performance. They may not
understand the dynamics of air duct silencing or the
significance of faceted wall panels, but they do enjoy
the moving sound of a Bach concerto or a Prokofiev
symphony.
" Registered
Corporation

trademark

Environmental

Elements

Other credits:
Architects

Hammel Green & Abrahamson, Inc.,
St. Paul
Associate Architects Hardy Holzman Pfeiffer Associates,
New York

Structural Engineers

Meyer, Borgman & Johnson, Inc.
Minneapolis

Construction Consultants
Contractor

Naugle-Leek Assoc., Inc.
Minneapolis
Egan.& Sons, Minneapolis

BERKEY COLORTRAN is pleased to announce that
their New York Sales Office will be relocated on September 15th, 1975 to:
BERKEY COLORTRAN, INC.
222 East 44th Street
9th Floor
New York, New York 10017
(212) 682-5040
You are invited to visit the StudiolTheatre Showroom
where the complete line of Berkey Colortran equipment
will be on display.

THEATRE DESIGN AND TECHNOLOGY

USITT

Table of Contents for the Digital Edition of Theatre Design & Technology - Winter 1975