Theatre Design & Technology - Feb 1974 - 38

Although the VISiting program primarily was oriented

has been reflected more than once, whether "early" or

on the meeting with theatres and universities, I took every

"late ". Energy that has oeen reflected only once may be
referred to as "F irst" or "Primary" reflections.

opportunity to learn about the countryside, towns and
their arch itecture.
Here I went through historically developed cities Iike
Pittsburgh whose structure is rather familiar for
Europeans, but also through towns Iike Los Angeles which
are not equal to their task as the most econom ic
communication centres.
A very favorable combination between both is
represented by a city like San Francisco. But which other
one is like this? This very favorable topographical and
townplanning situation (site) provides an extremely
esteemed and friendly town structure for living and
communication, which never denies the North American
planning checkerboard system.
An intensive meeting with the architecture of Frank
Lloyd Wright and Richard Neutra became the
architectonic high point with social and dwelling houses
like the Guggenheim Museum, the Bakersfield Culture
Centre, Churches and the famous Fallingwater House on
Bear Run.
Everywhere I was received cordially as a guest of the
local members of USITT. They managed this immense
program in such a short time! So I was able to get this
survey over country, town, architecture and especially
theatre.
I express my heartiest gratitude to the US I nstitute for
Theatre Technology for making it possible for me to have
my first visit in the USA.

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characteristic of speech recording studios and for that
reason sometimes designed out of halls (unfortunately) by
acoustical engineers in the days preceding Dr.
Beranek's massive concert hall research project.

Leo

Diffusion Surface: A surface that is irregular or convex
and so reflects sound energy in many directions, as a
white matte surface does for light, as opposed to a
concave surface, which focuses sound, or a flat surface,
which reflects sound in only one direction.
Micro Diffusion Surface: A small diffusion surface or one
that is particularly effective at high frequencies.
I nner System: A system of sound reflectors, diffusing
surfaces, or other acoustical devices within the actual
acoustical boundaries of a room and not including the
boundary surfaces.
Sound
Pressure
Level:
Expressed in decibels,
mathematically equal to 20 times the logarithm, to the
base 10, of the ratio of the actual sound pressure to a
reference sound pressure. The accepted reference sound
pressure is approximately the minimum sound pressure a
person with normal hearing can hear, at the frequency
where the ear is most sensitive. The usual expression for
the actual intensity of a sound field, as opposed to
subjective loudness ratings.
Couple Volumes: To insure that the characteristics of a
sound field in one volume affects the sound field in
another.

DESIGN CONSIDERATIONS . .. Cont.
GLOSSARY OF TERMS
Direct Sound Field: The sound energy directly radiated
from a sound source, without reflections.
Early Arriving Sound Field: The sound energy arriving at
a listener's ear (or at measurement or recording
equipment), soon after including the direct sound energy,
soon enough to add to the clarity of speech and music.
Most researchers agree that the actual time limits for
"soon" are somewhere around 30 or 50 milliseconds.
Sound arriving 50 milliseconds after the arrival of the
direct sound is "Late".
Reverberant Field: The sound energy in a space excluding
the Direct Sound Field: in other words, all reflected
sound energy, including single, double, and multiple
reflections.

Couple Directly: To couple without electroacoustic
(sound system) devices or intervening volumes.
Coupling Capability: The degree to which the
characteristic of one sound field can affect another sound.
Energy flows between them.
Time Frame: A duration of time, taken from a longer
period.
Diffusion Pattern: The degree of randomness of the sound
energy reflected from a sound-diffusing surface.
Cross-Stage Diffusion Pattern: Same as above, but within
the stage enclosure, the concert hall's "sending end", etc.
Important in providing the ability of orchestra members
to hear each other.
Use of Scrim: " .. _.articulating .shell must be coupled to

before 30 or 50 milliseconds.

the stage house with a
scrim curtain" .... : The
characteristics of the sound within the articulating shell
must affect the sound field within the stagehouse but at
the same time, the stagehouse must be visually screened
from the audience. Sound can pass through a scrim, so

Secondary Sound Field: All reflected sound energy that

scrim shou Id be used.

Early Secondary Reflections: Reflected sound energy that
has been reflected more than once, and that arrives at the
listener's ears (or the measurement or recording location)

38

Bass Lift: A boost in the bass response of a room or hall,
as compared with the mid-range and treble response. A
characteristic of nearly all good concert ha lis. Not a

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THEATRE DESIGN AND TECHNOLOGY

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FEBRUARY. 1974
Table of Contents for the Digital Edition of Theatre Design & Technology - Feb 1974
