An Improved Instrument for Localising or Determining the Direction of Sound-producing Instruments.
Year: 1888

page_text: Date of Application, 17th Oct., 1888
Complete Specification Left, 5th July, 1889-Accepted, 24th Aug., 1889
INUY IDIONAL DIATION.
An Improved Instrument for Localising or Determining the Direction
of Sound-producing Instruments.
I, CHARLES MARIE MICHEL DE GOYON, Duc de Feltre, of 59 Rue St. Dominique,
Paris, France, do hereby declare the nature of this invention to be as follows:-
This Invention relates to an improved topophone or instrument for determining tho
direction of origin of sounds. The instrument consists essentially of a number of micro-
phones, preferably two, mounted on the opposite sides of a box which is movable about
an axis, each microphone being in circuit with a telephonic receiver. The observer
applies the receivers to his ears and, guided by the difference of intensity of the
sounds emitted by the two instruments, adjusts the box about its axis until the sounds
perceived are of equal intensity.
Reference is to be had to the accompanying drawings forming part of this specifi-
cation, in which figure 1 is a diagram representing a plan of the box carrying the
microphones and the telephonic receivers. Figure 2 is a diagram shewing, in sectional
elevation, the whole apparatus, the details of construction of which, however, may be
varied. Similar letters of reference serve for like parts in both figures.
A B; are the two microphones mounted on the opposite sides of a box C of cubical
form mounted above the roof of a cabin upon a vertical shaft D, which is mounted to
revolve in a footstep bearing on a table E. within the cabin of which the walls are
thick and, if necessary, padded. Upon the lower part of the shaft is keyed an
index F which turns with the shaft over a dial H, divided in degrees, fixed on the
table. The microphone A is in circuit with a telephonic receiver a and the micro-
phone B with a receiver b.
When the apparatus is in use, a battery current is switched through each of the
circuits, and the receivers a and b are applied to the two cars of the observer.
Suppose the sound of a trumpet to be emitted at a certain distance from the
cabin. If the side of the box on which the microphone A is mounted be so
directed that the right line from the source of sound strikes its face, even at a
very acute angle, the right ear of the observer in the cabin will be more strongly
impressed than the left ear and the sound will appear to come from the right,
the contrary impression being produced if the right line from the source of sound
strikes the face of the opposite side of the box on which the microphone B is
mounted. When, by turning the box C in azimuth, the impressions produced
upon the two ears are equal, the median plane X X', of the two microphones
will be perpendicular to the direction of the source of sound. It is, therefore,
only necessary to turn the shaft D until the sound does not preponderate towards
either side. The shaft may be turned by means of the index F which may be
keyed on the shaft at any angle relatively to the median plane X X of the two
microphones. Suppose that the observer has in this way brought the index to
division 75 of the dial, he should then turn it either to right or left through an
arc of 90°. If it be turned say to division 165 the sound will appear to be received
either in the right or left ear, as the case may be; if it be heard in the right ear
the microphone A will be perpendicular to the direction of the sound and facing
directly towards its source, and if heard in the left ear it is the microphone B which
is facing directly towards, and is perpendicular to the direction of the sound. If
now, an alidade be fixed upon the top of the box Cin the median plane X X¹ of the
two microphones the plane of the two sights of the alidade will coincide with the
source of sound at the moment when the index F is brought to the division 165. If
the observer has operated imperfectly, the error may be easily measured by the
angle through which the alidade box, shaft, and index, must be moved to the right or

page_text: left of the division 165, in order that the plane of the sights shall coincide with the
source of sound. A wind vane is mounted on the upper end of the shaft D to enable
the angle which the direction of the wind makes with the direction of the sound, to
be measured. By adjusting the alidade (which turns as one with the box C,
shaft D, and index F,) in the plane of the wind vane, tho index shews on the dial
the direction of the wind to right or left of the division 165, the hypothetical
direction of the observation made.
With this simple combination of apparatus, observations may be made with great
precision. The apparatus may be applied to various purposes, but is especially
designed as a guide and warning to navigators who, by its means, are enabled to
recognise and register the direction of acoustic signals which cannot be distinguished
by the unaided.car with sufficient precision to avoid collisions in foggy weather.
T: 171
1000
C. M. M. DE GOYON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
An Improved Instrument for Localising or Determining the Direction
of Sound-producing Instruments.
I, CHARLES MARIE MICHEL DE GOYON, Duc de Feltre, of 59 Rue St. Dominique,
Paris, Franco 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 :-
This Invention relates to an improved topophone or instrument for determining the
direction of origin of sounds. The instrument consists essentially of a number of
microphones, preferably two, mounted on the opposite sides of a box, which is movable
about an axis, each microphone being in circuit with a telephonic receiver. The
observer applies the receivers to his ears and, guided by the difference of intensity of
the sounds emitted by the two instruments, adjusts the box about its axis until the
sounds perceived are of equal intensity.
Reference is to be had to the drawings left with the provisional specification, in
which figure 1 is a diagram representing a plan of the box carrying the microphones
and the telephonic receivers. Figure 2 is a diagram shewing, in sectional elevation,
the whole apparatus, the details of construction of which, however, may be varied.
Similar letters of reference serve for like parts in both figures.
A B, are the two microphones mounted on the opposite sides of a box C of cubical
form mounted above the roof of a cabin upon a vertical shaft D, which is mounted to
revolve in a footstep bearing on a table E within the cabin of which the walls are
thick and, if necessary, padded. Upon the lower part of the shaft is keyed an index F
which turns with the shaft over a dial H, divided in degrees, fixed on the table. The
microphone A is in circuit with a telephonic receiver a and the microphone B with a
receiver b.
When the apparatus is in use, a battery current is switched through each of the
circuits, and the receivers a and b are applied to the two ears of the observer. Suppose
the sound of a trumpet to be emitted at a certain distance from the cabin. If the side
of the box on which the microphone A is mounted be so directed that a right line
from the source of sound strikes its face, even at a very acute angle, the right ear of
the observer in the cabin will be more strongly impressed than the left ear and the
sound will appear to come from the right, the contrary impression being produced if
the right line from the source of sound strikes the face of the opposite side of the box
on which the microphone B is mounted. When, by turning the box C in azimuth,
the impressions produced upon the two ears are equal, the plane X X¹³, intersecting
the two microphones will be perpendicular to the direction of the source of sound.
It is, therefore, only necessary to turn the shaft D by means of the index F as a

page_text: handle until the sound does not preponderate towards either side. Suppose that the
observer has in this way brought the index to division 75 of the dial; he should then
turn it either to right or left through an arc of 90°. If it be turned say to division 165
the sound will appear to be received either in the right or left ear, as the case may be ;
if it be heard in the right ear the microphone A will be perpendicular to the direction
of the sound and facing directly towards its source, and if heard in the left ear it is
the microphone B which is facing directly towards, and is perpendicular to the
direction of the sound. If an alidade be fixed upon the top of the box C in the
plane X X the plane of the two sights of the alidade will now coincide with the source
of sound at the moment when the index F is brought to the division 165. If the
observer has operated imperfectly, the error may be easily measured by the angle
through which the alidade, box, shaft, and index, must be moved to the right or left
of the division 165, in order that the plane of the sights shall coincide with the source
of sound. A wind vane is mounted on the upper end of the shaft D to enable the
angle which the direction of the wind makes with the direction of the sound, to be
measured. By adjusting the alidade (which turns as one with the box C, shaft D, and
index F) in the plane of the wind vane, the index shews on the dial the direction of
the wind to right or left of the division 165, the hypothetical direction of the observa-
tion made.
With this simple combination of apparatus, observations may be made with great
precision. The apparatus may be applied to various purposes, but is especially
designed as a guide and warning to navigators who, by its means, are enabled to
recognise and register the direction of acoustic signals which cannot be distinguished
by the unaided ear with sufficient precision to avoid collision in foggy weather."
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is :-
The herein described improved instrument for determining the direction of sounds;
consisting essentially of two microphones in circuit with two telephonic receivers
mounted to revolve about a common axis so that, when sounds of equal intensity are
perceived by the two ears, the true direction of the sound will coincide with a line
bisecting the angle which the microphones make with each other or with the median
plane parallel with the microphones and passing through their axis of rotation, as
specified.
Dated this 5th day of July 1889.
C. M. M. DE GOYON, Duo DE FELTRE.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.