Improvements in Topophones or other Sound-receiving Instruments.
Year: 1897

page_text: Improvements in Topophones or other Sound-receiving Instruments.
I, LEVI E. THORNE, of Havemeyer Building, 26, Cortlandt, Street, City and State
of New York, United States of America, Gentleman, do hereby declare the nature of
this invention to he as follows:-
The main objects of this invention are to improve the sound-conducting properties
of topophones or other sound-receiving instruments, and to protect these instruments
from the rush of air to which they are frequently exposed and thereby prevent the
shrill whistling around their edges, which has been found to interfere materially with
their efficiency.
According to this invention I employ two substantially trumpet-shaped sound-
receivers turned back-to-back. In instruinents of this description it is found that if
the sound-receivers are of the usual symmetric form, some of the sound-waves
impinge upon the walls at such an angle that they rebound out of the mouth through
which they had previously entered and consequently become lost instead of being
deflected towards the conducting tubes.
To overcome this difficulty I curve or externally bulge the wall, of each of the
sound-receivers so that a pocket or recess is formed at the interior on the side adapted
to receive the sound-waves, this pocket or recess serving to collect the said sound-
waves and direct them towards the conducting tube which is preferably situated nearer
to the recessed than the non-recessed part.
To prevent or minimise the entrance into the receiver of sound coining from the
back thereof I surround the mouth of such receiver with a wide and preferably hollow
flange, and to prevent the conduction of sound from one to the other of the receivers
I secure them in, or to, or suitably enclose their lack portions in a casing and fill the
space enclosed between the receivers and the casing with a suitable non-conductor or
bad conductor of sound, the space within the flange, when this latter is made hollow,
being similarly filled with sound-insulating material.
To protect the instrument from the rush of air as hereinbefore mentioned I provide
over the mouth of each receiver a covering of silk or other suitable material preferably
applied by means of doine shaped wirework which may extend over the above named
flange, the covering of silk or other material being tightly stretched over the said
wirework so as to prevent any fluttering of the covering.
Dated thin and day of N.
11007
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.

page_text: I, LEVI E. THORNE, of Havemeyer Building, 26, Cortlandt Street, in the City
and State of New York, United States of America, Gentleman, do hereby declare
the nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
66
The main objects of this invention are to improve the sound conducting properties
of sound receiving instruments known by various names such as "cophones" and
topophones" and to protect these instruments from the rush of air to which they
are frequently exposed thereby preventing the shrill whistling sound around their
edges which has been found to interfere materially with their efficiency.
In instruments in which there are employed two sound-receivers of trumpet shape,
or of a shape approximating thereto, and set back-to-back and usually called
topophones, it is found that if the sound-receivers be of the usual symmetric form
some of the sound-waves are lost in consequence of their impinging upon the internal
"walls of the sound receivers at such an angle that the said sound waves rebound and
return out of the mouth through which they previously entered instead of being
deflected towards the conducting tubes.
To overcome this difficulty, I curve, or externally bulge, the wall of each of the
sound-receivers so that a pocket, or recess, is formed at the interior on the side which
normally receives the sound-waves, this pocket, or recess, serving to better collect the
said sound-waves and direct them towards the conducting tube, which is preferably
situated nearer to the recessed than to the non-recessed part.
To prevent, or minimise, the entrance into the receivers of sound coming from the
backs thereof, I surround the mouth of each receiver with a wide flange, and, to prevent
the conduction of sound from one to the other of the receivers, I may secure them in,
or to, or suitably enclose their back portions in, a casing, and fill the space, enclosed
between the receivers and the casing, with a non-conductor, or bad conductor, of
sound, the space within the flange, when this latter is made hollow, being preferably
filled with sound-insulating material.
To protect instruments of this character from rush of air, and prevent the aforesaid
whistling sound, I provide, over the mouth of each receiver, a covering of silk, or
other suitable material, preferably in the case of topophones applied by means of
dome-shaped wire structure, which extends over the above named flange, the covering
of silk, or other material, being tightly stretched over the said wire-structure so as to
prevent fluttering of the covering.
I will describe my invention with reference to the accompanying drawings but I do
not limit the application of iny invention to the form of instrument to which I have
illustrated it as applied.
Figure 1 is an elevation of a device embodying my improvements, one of the
receivers having the screen applied to it. Figure 2 is a central vertical section of
the receivers. Figure 3 is a face view of one of the receivers. Figure 4 is a
horizontal section on line 4-4, Figure 3. Figures 5 and 6 are, respectively, a side
and front view of the support for the screen. Figure 7 is a section of a form of
receiver hereinafter referred to.
A A represent the sound-receivers. They are arranged so that their mouths, or
flaring open ends, point in opposite, or nearly opposite, directions, and are rotatable
in order that their mouths may be brought into proper position. For this purpose
they are shewn as being connected to the support B which is mounted so that it
can be rotated. The conducting tubes c are shewn as passing into the top of the
support B and out at the side thereof where flexible tubes C, or other sound-

page_text: conduits, provided with ear pieces E are attached as shewn in Figure 1. The
said tubes preferably extend downward, as shewn, but they may extend in any other
direction desired. .
In topophones the sound-receivers have heretofore, so far as I am aware, always
been so shaped that a portion of the rear, or aft, part of the inside wall of the mouth
of the receiver is convex, as indicated by the dotted liner in Figure 2.
This shape
of the receiver-wall tends to reflect such sound-waves as may enter the receiver's
mouth and strike such convex part. As the only sound-waves which directly enter
the mouth of the receiver, when the instrument is faced close to the direction from
which the sound comes, strike this convex portion and are, more or less, reflected
outwards thereby, and are therefore partially lost to the sense of the observer, it
follows that the instrument thus made loses a certain degree of its efficiency and is
not so sensitive as it would be were all the sound collected and conducted to the ear
of the observer. One feature of my invention consists as aforesaid in making the
receivers so as to better collect the sound and to prevent the loss by reflection in the
said manner. For this purpose I make the side of the sound-collecting receiver
adjacent to the mouth, or open end, to belly outward on its rear, or after side, as.
indicated at a in Figures 3 and 4. It will be readily seen that owing to this
formation any sound waves which enter the mouth of the receiver are caught and
directed towards its conveying portion, and the liability to loss by reflection of the
sound waves is reduced to a minimum. I also prefer to make the inner wall a¹ of
the receiver that is, that part which is opposite to the open mouth-straight, or
nearly so, from a line about opposite to the centre of the mouth-opening of the
receiver to the contracted portion c as shewn in Figures 1 and 2. The upper part a²
of the inner wall, or that portion which is farthest from the contracted part c, is
curved so as to be convex on its inner side till it joins, or merges into, the flat.
portion a¹ of the wall, as represented in Figure 2. I find that this way of shaping
the rear wall of the receiver is preferable to that represented in full lines in Figure 7
where the rear wall extends first backward, or away from the mouth in its upper
portion, and then forward, or toward the mouth, in its lower portion, instead of being
of the shape aforesaid as indicated by the dotted lines.
D is the aforesaid flat flange which surrounds the mouth of each receiver and
extends outward in a plane transverse to the axis of the receiver at its mouth, or
open, end.
These flanges operate to increase the sensitiveness of the instrument,
cutting off, in a very perfect manner, the sound from that receiver which is turned
away from the direction of the sound and directing into that receiver, which is
'operating, a greater amount of sound than it would otherwise receive.
I have shewn a flange which extends completely around the mouth of the
receiver, but a flange extending only partly around the said mouth may be used if
desired.
The screen is represented at G Figure 1 and consists, preferably, of silk, or similar
closely woven material, which, while not materially interfering with the free
transmission of sound, will yet oppose the entrance of wind. This screen is supported
by the sound-receiver and is stretched over the open mouth thereof, the edges of which
it covers, so that it operates to prevent the whistling of the wind across such edges.
When the screen is applied to topophones I prefer that there should be combined
with the screen a light screen support H, Figures 5 and 6, over which the screen
may be stretched, as thereby all liability of the screen fluttering is avoided. The
support H may be secured to the flaring end of the receiver in any suitable way.
I prefer to secure it by housing the frame h of the support H in a recessed lip
around the periphery of the flange D as shewn at h² at the right side of
Figure 2. When upon the receiver, it may be held in place by a screw, or other
suitable means. The screen may be stretched by any suitable means-as, for
example, a draw-string g, Figure 1,-the edge of the material of which the screen
is composed being drawn over the edge of the flange D, until the screen is
taut, when it is secured by the draw-string. Other means may of course be used
:

page_text: or the same purpose. A screen and support of this character are very light
and add but little to the size of the instrument.
The drawing shews the screen applied to a flanged topophone but it may be
applied to ordinary topophones or eoдhones or like instruments to protect the
instrument from rush of air.
I prefer to add to the after side of the mouth of each receiver a projection as
shewn at y at the right hand side of Figure 2 which projection stands out from the
edge of the flange D and forms a sound conductor which is slightly inclined inwards,
as clearly shewn in Figures 2 and 3.
I have shewn the flange Das being flat and in one piece but it may be made hollow
that is with sides enclosing a space in which material non-conductive of sound is
placed, as shewn at the right hand side of Figure 2.
Although I have shewn the invention as applied to an instrument wherein the
sounds are conveyed by tubes to a person beneath, I do not limit myself to this as
for example the instrument may be formed so as to be mountable upon the shoulder
of the person using it and with passages leading directly from the receivers to the ears
of the user.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :-
1. A sound receiving instrument comprising a sound-receiver, or receivers, of
funnel, or trumpet, shape, the mouth of which, or of each of which, is provided with
a flange projecting outward in a plane transverse to the axis of the receiver at its
mouth; substantially as, and for the purposes, herein before described.
2. In a sound-receiving instrument, a receiver for collecting the sound, the outer
flaring portion of which is bellied on its rear part adjacent to the mouth, substantially
as, and for the purposes, herein before described.
3. The combination with the receiver of a sound-receiving instrument, of a
wind-screen supported across and covering the edges of the mouth of the receiver,
substantially as, and for the purposes, herein before described.
4. The combination with the receiver of a sound-receiving instrument, of a screen
support carried by the receiver and arranged over the mouth thereof, and a wind-
screen arranged over the said support, substantially as, and for the purposes, herein-
before described.
5. The arrangement and combination of parts constituting a sound-receiving
instrument as herein before described and illustrated in the accompanying drawings.
Dated this 2nd day of August 1898.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.