Evening star., 1953-05-22
Quietest Spot on Earth
Is Just Outside District
Navy Laboratory Room
Is Incapable Of Echoes
By Thomos R. Henry


The quietest spot on earth is
maintained by the Navy just outside
Washington.
Something of the absolute noiseless-
ness of airless outer space is attained
in the "anechoic room" Of the Naval
Ordnance Laboratory. which is de-
scribed in Navy publication as "look-
ing as If it might have been intended
as the set for some horror movie"
It is designed for study of pure
sounds uncontaminated by echoes or
any extraneouS noises. Walls, ceiling
and floor are lined completely with
caramel-colored fibre glass wedges, all
mounted so that their tips point
toward the center Of the dimly lighted
chamber.
The idea, Navy scientists explain, is
to have working space for acoustic
experiments sufficiently large so that
such sound as does come bouncing
back from the walls will be so weak
that it will have little or no effect
on the experiment in progress. Sound
waves diminish in intensity not so
much due to the distance they travel
from their source as to the way they
spread out. The design of the walls
makes the room almost completely
dead" In addition to extra-thick
walls which isolate it from the main
laboratory building there is a two-inch
layer of fiber glass and a two-inch
layer of cork on floor, walls and
ceiling. Finally. there are thousands
of wedges completely lining the cham
ber and pointing into it.
Virtually Anechoic.
The room is not completely without
reflection but is about 100 per cent SO
for all sound waves within the audible
range, from 20 to 5000 cycles.
Equipment to be tested is suspended
from an overhead crane system which
is all electric and fully remote Com
trolled. Nobody is in the room when a
test takes place. The room is completely
air-conditioned with devices for precise
control of humidity and temperature.
Any experimental problem in which
sound is turned loose in space. the Navy
scientists explain, requires an echoleSS
room to control the study effectively.
The idea had its origin in Germany.
During the war room on the German
model was constructed by the Bell Tele-
phone laboratories. The Navy has i'm
proved on the basic design. Other ane-
choic rooms in existence are designed
for some special purposes. The Nays
is the largest, best equipped, most ver-
satile and quietest of any devised
to date.
In the Army the boys generally
called it axle grease.
It was the stuff designated as but
ter" which was issued to troops at the
front-or, for that matter, about any,
where outside the United States.
Perhaps it was-or maybe it wasn't
better than no butter at all, but doubt
less the fellow who invented it was
good-hearted fellow who wanted to
help the soldiers. Now Agriculture De-
partment chemists have developed a
far superior butterlike process for
military use from which it will be
hardly possible to distinguish real fresh
creamery butter.
Butter and margarine" says the
Bureau of Chemistry's announcement.
spread easily only within a limited
range of temperature. At temperatures
as low as 20 degrees F. both are hard
and difficult to spread. At temperatures
as high as 100 they melt. When either
product is alternately cooled and
warmed it is likely to separate into
two parts, one containing water and
the other fat.
Easily Spread.
Now spreads containing combina-
tions of liquid vegetable OH, modified
fats, vitamins and flavoring have been
developed at the Northern regional
laboratory. These mixtures can easily
be spread on bread at temperatures from
zero Fahrenheit to ITO or higher. The
'butters,' however, can be patterned
for different localities, since the actual
temperature range at which they will
retain their qualities depends on the
nature of the oils and fats used"
They can be favored in almost any
way desired-especially in ways to
make them indistinguishable from
fresh butter.
The work has been carried out in
cooperation with the Army Quarter
master Corps. Now pilot plant tests
are being conducted to determine
whether the products can be produced
commercially without much modiflca-
ton Of present equipment.