Evening star., 1924-03-18
ACCURACY Demanded
| BY RADIO AUDIENCE
Faithful Transmission Possible
Only by Careful Scientific
Study.
LONG RESEARCH NECESSARY
Fans BecQying Daily More Critical
Of Programs.
LONG RESEARCH NECESSARY

When radio hroadcasting started,
the fan who had any sort of a set
at all drew gasps of wonder from
his friends when they heard some
local station grinding out phonograph
music A year later. and the craze
was for long distance records. Then
came loud speak whose raucous
h!eatings were an insult to the pub
lies musical good taste.
Developed by men Of brief expert
ence in the art. and having little or
no knowledge of the acoustic prin-
ciples involved. many of the early
ioud-speakers were merely glorified
telephone receivers. fitted to a horn
and designed 10y guess and by gosh"
Now that radio is settling down to
d means OF entertainment that must
stand on its own merits in Competi-
tion with other forms the public is
demanding a quality and volume Of
reproduction so faithful to the orig
inal that the listener can close his
eyes eyss and forget that he is not in the
studio or concert hall
Such faithful transmission and re-
production of Il radio program is pos
slbie only when every link in the
chain is carefully designed and skill
fully operated
The system must not fail to trans
NIT the full range of tones; it must
mot add any tones of its own, rec
ogniZed AS blur or "fuZz," and caused
by overlooking one or more ele-
ments; it must not introduce noise,
and it must give enough volume FOR
comfort. yet not 50 much as to make
the lower tones heavy.
Research Necessary.
To avoid these troubles. "cut and
try" methods with the human ear
and memory as guides will not serve.
PreSent-day achievements have been
possible only because of measure
ment methods and standards resting
en- fundamental researches extending
back more than generation. The
high-quality carbon microphone of
today is direct descendant of the
granular carbon transmitter on
which Bell system engineers were
working as early as 1886.
Some of the practical details which
spoil radio listeners enjoyment were
pointed out in a recent paper by W.
II. Martin of the American Telephone
and Telegraph Company and DR.. Har-
vey Fletcher of the Western Electric
Company.
Perfectly intelligible speech can be
transmitted in which tones ranging
from 500 to $500 cycles only are en-
ployed, but in order to obtain nat
uralness of effect comparable to that
of the original. the range must be
extended at both ends to include 100
cycles and 5000 cycles: if music, also
must still be further extended to
1000 cycles or more. To include so
long range requires close atten-
ton to the receiving apparatus, and
the tendency for carelessly- designed
mlcrophones, transformers, lines. etc,
lNxtL \ \
In order to satisfy a radio audience
that is growing rlore and more criti-
cal. 1t Is necessary to transmit music
with such naturalness that the list
ener can close his eyes and forget
that he is not in the studio or con-
cert hall In other words, it must
reach him in the form in which he
would care to hear ii if he were
Tree to choose his own location with
respect to the source of sound.
Some Re.erberations Necessary.
In the arrangement of a broadcast
ing studio room which gives no re-
Eerberatfon is just as bad as one Civ
Ing too much. 1t is generally recog-
nized that bare room is undesirable
as the reverberations cause one note
or syllable to follow over into the
next, producing an unpleasant tumble
or sound; but il is Il very common
error to cover the walls, floor and
NcHlnS ol tHe Slu0-O as completely as
possible with sound absorbing ma
teriai. cutting off all echo and making
the music sound dead" This con-
d1tion also makes it very difficult for
Il singer or violinist to keep on the
key. as they are accustomed to get
ting the pitch of each note from the
reverberation OF the preceding one.
When. as is often the case, the pro-
gram is presented in an assembly
room or concert hall. it is obviously
impossible to change the acoustic
properties of the room. The best
solution of the problem then is in
properly locating the microphone
transmitter. when a symphony con-
cert is broadcast. the best place for
the microphone has been found to be
from thirty to fifty feet in front of
the orchestra and ten to twenty feet
from the ceiling. This location picks
up the sound of the orchestra as a
whole, and does not catch too much
the audience. 1t is not desirable to
scatter several microphones through
the orchestra, as with this arrange
1nent the noises from part of the in
SIumentS will be transmitted. with
greater intensity than that from
others, and the balance of the en-
semble will be lost.
Vary AmpliGcation.
Some idea of the difficulty of artis-
tically transmitting program by
radio is given by the fact that in one
selection by large orchestra, the
volume of sound produced may be
100000 times greater at one time
than at another. AS no broadcast
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