A few words should be written concerning the popular notion that
wires and sounding boards are effective in curing faulty acoustics.
Experiments and observations show that wires are of practically no
benefit, and sounding boards can be used only in special cases. Wires
stretched in a room scarcely affect the sound, since they present too
small a surface to disturb the waves. They have much the same effect on
sound waves that a fish line in the water has on water waves. The idea
has, perhaps, grown into prominence because of the action of a piano
in responding to the notes of a singer. The piano has every advantage
over a wire in an auditorium. It has a large number of strings tuned
to different pitches so that it responds to any note sung. It also has
a sounding board that reinforces strongly the sound of the strings.
Finally, the singer is usually near the piano. The wire in the
auditorium responds to only one tone of the many likely to be present,
it has no sounding board, and the singer is some distance away. But
little effect, therefore, is to be expected.
The author has visited a number of halls where wires have been
installed, and has yet to find a case where pronounced improvement has
resulted.[11] Sabine[12] cites a case where five miles of wire were
stretched in a hall without helping the acoustical conditions. It is
curious that so erroneous a conception has grown up in the public mind
with so little experimental basis to support it.
_Sounding Boards._--Sounding boards or, more properly, reflecting
boards, have value in special cases. Some experiments are described
later where pronounced effects were obtained. The sounding board should
be of special design to fit the conditions under which it is to be used.
_Modeling New Auditoriums after Old Ones with Good Acoustics._--Another
suggestion often made is for architects to model auditoriums after
those already built that have good acoustical properties. It does not
follow that halls so modeled will be successful, since the materials
used in construction are not the same year after year. For instance,
a few years ago it was the usual custom to put lime plaster on wooden
lath; now it is frequently the practice to put gypsum plaster on metal
lath, which forms an entirely different kind of a surface. This latter
arrangement makes hard, non-porous walls which absorb but little sound,
and thus aggravate the reverberation. Further, a new hall usually is
changed somewhat in form from the old one, to suit the ideas of the
architect, and it is very likely that the changes will affect the
acoustics.