A METHOD OF AND DEVICES FOR THE PREVENTION OF DISTURBING SOUNDS IN ACOUSTIC APPARATUS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, HERBERT JOHN HADDAN, of 67, Strand, in the City of Westminster, Civil
Engineer, do hereby declare the nature of said invention for A METHOD OF AND
DEVICES FOR THE PREVENTION OF DISTURBING SOUNDS IN ACOUSTIC APPARATUS,
a communication to me from abroad by Adolf Rettig, attorney at law, of Saar-
brücken, through his agents Wirth and Company, of Frankfurt a/M. Germany, to
be as follows:-
.
This invention has for its object to prevent the discordant sounds which occur in
acoustic apparatus, for instance speaking or hearing tubes, by vibrations which
continue long after the exciting cause has ceased to act, and thereby interfere with
the subsequent vibrations so as to modify their effect.
It is therefore desirable to interrupt or shorten the vibrations of the apparatus,
which may be effected by dividing the acoustic body so as to obtain a number of
small vibrating sections. For this purpose I distribute over the outer or inner
surface of the acoustic body, or around the mouth of the same, or around the sound
conducting tube a suitable number of dampers adapted to be brought in contact
with the vibrating surface and thereby to interrupt its vibrations.
According to the pressure exerted upon the dampers, and the number and
relative positions of dampers which are simultaneously brought into action their
effect may be increased or diminished. In proportion as the vibrating sections are
reduced in size, their vibrations will be shorter, and therefore the sound higher.
A convenient way of applying such dampers consists in surrounding the mouth
of the acoustic apparatus with a split ring containing a suitable number of radial
set screws each of which has a square hole for introducing a key and may be
brought in contact with the apparatus. The ends of the ring are provided with
flanges and connected by a screw by the turning of which the ring may be con-
tracted or expanded, so as to vary the pressure of the set screws upon the rim of

page_text: the acoustic apparatus. The ring itself is kept out of contact with the acoustic
apparatus, and the set screws may be provided with washers or cushions of india
rubber leather, or other soft material. Each set screw may be turned independently
of the others and constitutes a damper which may be placed in or out of contact
with the mouth of the acoustic apparatus.
Dampers for conducting tubes may also be formed by set screws carried by a
split ring surrounding the tube. Two or more rings with set screws may be placed
side by side.
"
The same. method of preventing disturbing sounds is also applicable to concert
rooms or halls of public buildings.

page_text: I, HERBERT JOHN HADDAN, of 67 Strand, in the City of Westminster, Civil
Engineer, do hereby declare the nature of said invention for A METHOD OF and
DEVICES FOR THE PREVENTION OF DISTURBING SOUNDS IN ACOUSTIC APPARATUS,
a communication to me from abroad by Adolf Rettig, of Saarbrücken, in the
German Empire, Attorney at Law, and in what manner the same is to be per-
formed, to be particularly described and ascertained, in and by the following
statement:-
This invention has for its object to prevent the discordant sounds, which occur
in acoustic apparatus, for instance speaking or hearing tubes, by vibrations which
continue long after the exciting cause has ceased to act and thereby interfore with
the subsequent vibrations so as to modify their effect.
It is therefore desirable to interrupt or shorten the vibrations of the apparatus,
which may be effected by dividing the acoustic body so as to obtain a number of
small vibrating sections. For this purpose I distribute over the outer or inner
surface of the acoustic body, or around the mouth of the same, or around the sound
conducting tube, a suitable number of dampers adapted to be brought in contact
with the vibrating surface and thereby to interrupt its vibrations.
According to the pressure exerted upon the dampers, and the number and
relative positions of dampers which are simultaneously brought into action, their
effect may be increased or diminished. In proportion as the vibrating sections are
reduced in size, their vibrations will be shorter, and therefore the sound higher.
A convenient way of applying such dampers consists in surrounding the mouth
of the acoustic apparatus with a split ring containing a suitable number of radial
set screws each of which has a square hole for introducing a key, and may be
brought in contact with the apparatus. The ends of the ring are provided with
flanges and connected by a screw, by the turning of which the ring may be
contracted or expanded, so as to vary the pressure of the set-screws upon the rim
of the acoustic apparatus, and the set screws may be provided with washers or
cushions of indiarubber, leather or other soft material. Each set-screw may be
turned independently of the others and constitutes a damper which may be placed
in or out of contact with the mouth of the acoustic apparatus.
Dampers for conducting tubes may also be formed by set screws carried by a
split ring surrounding the tube. Two or more rings, with set screws may be
placed side by side.
The same method of preventing disturbing sounds is also appliable to concert
rooms or halls of public buildings.
In the annexed drawings, which serve to illustrate the invention, Fig. 1. is an
axial section and Fig. 2 an end view of an acoustic apparatus furnished with
dampers. Figs. 3, and 4, show the application of dampers to conducting pipes.
A are screws inserted into the split ring B, and serving as dampers, C is a screw
for holding together the two ends or halves of the ring.

page_text: In order to adjust the apparatus properly, the person using the apparatus takes
a small screw key and while listening to the speaker sets those dampers in action
(by tightening the screws with the key) which are necessary for the removal of
the discordant sounds.
By tightening or loosening the screw, which unites the ends of the split-ring the
effect of the dampers set in action by him may be intensified or diminished. In
this manner the person may conveniently regulate the vibration of the instrument,
to suit the peculiarity of the room, the voice of the speaker and the individuality
of the ear.
Having now particularly described and ascertained the nature of said invention
and in what manner the same is to be performed, I declare that what I claim is
The method of preventing discordant sounds or interference of sounds in acoustic
apparatus, which consists in artificially dividing the acoustic body into vibrating
sections, by applying dampers at suitable distances from one another, either around.
the acoustic body proper or around its conducting tubes.