Improvements in the Method of and Means for Detecting the Direction or Source of Sound.
Year: 1891

page_text: Date of Application, 17th Mar., 1891-Accepted, 20th June, 1891
COMPLETE SPECIFICATION.
Improvements in the Method of and Means for Detecting the
Direction or Source of Sound.
We, NORTON PRENTISS OTIS, of Yonkers, Westchester County, New York,
and WALTER HUNNEWELL UNDERWOOD, of Yonkers, aforesaid, Manufacturers, 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 a method of and apparatus for determining more
accurately than has been possible heretofore the source or direction of sound. Up
to the present time great difficulty has been experienced especially upon vessels at
sea, in ascertaining by the sense of hearing or by any other known means, the
direction or the source from which sound proceeds as for example a fog signal and
consequently risks are incurred and disasters take place which would be largely
avoided by an adequate method and apparatus for accurately furnishing this
information.
In our invention we avail ourselves of the effect of sound waves upon any object,
for instance a diaphragm or diaphragms and although we shall hereafter refer to
diaphragms as constituting the wave receiving devices we wish it to be understood
that we include thereby anything sensitive to sound waves and adapted to indicate
or transmit their action in any way. This effect varies in degree according to the
exposure of the diaphragms more or less directly to the sound wave and in carrying
out our invention we arrange our apparatus with one, two or more vibrating
membranes or diaphragms set or moved to receive more or less directly the sound
waves proceeding from a signal or other source and connected with indicators which
may also be recorders whereby the extent of vibrations of each diaphragm or of a
single diaphragm when moved to different positions is indicated and as the varia-
tions and indications are greatest when the sound waves strike the diaphragm at
right angles, the determination of the relative movements of the diaphragm or
diaphragms will positively indicate the direction from which the sound proceeds.
Another means of carrying our invention into effect is by placing two or more
instruments each consisting of one or more diaphragms and their indicating or
recording devices at certain known points distant from one another; and when the
instruments are so placed as for example one at the bow and one at the stern of a
ship and perhaps a third at one side of the ship and midway between the other
two, with an indicating or a recording apparatus to which each is connected it will
be apparent that data will be thereby afforded upon which certain calculations may
be based, among which from the difference in the angles at which the sound waves
strike the diaphragms in the different instruments the distance and source as well
as the direction of a sound may be approximately (at least) calculated, and such
result may be reached by noting upon a common indicator or recorder the interval
of time between the contacts of the sound waves with various instruments.
For the purpose of illustrating our invention we have shown in the accompanying
drawing certain means which are effective but we wish it to be understood that
they are merely examples of different apparatus which may be employed for this
purpose:-
In the said drawing
Fig. 1 is a perspective diagrammatic view illustrating the principle of operation
of our invention.
Fig. 2 illustrates a modification.

page_text: Figs. 5, 6 and 7 illustrate modifications.
Fig. 8 illustrates the arrangement of the apparatus upon a vessel.
Fig. 9 is a view illustrating the construction of one of the receivers.
Fig. 10 is an enlarged diagrammatic illustration of the receiving apparatus con-
nected with a series of indicators.
Fig. 11 represents the stand enclosing the indicator apparatus.
Figs. 12 and 13 are views illustrating modifications.
Before describing the actual construction of an operative apparatus we will refer
to the diagrammatic view Fig. 1 which illustrates the principle of operation involved
in our invention.
In said figure there are four indicators A set in four different positions and each
consisting of a diaphragm or membrane 1 mounted or supported in any suitable
manner so as to vibrate readily under the action of sound waves and each connected
to operate an indicating device shown in Fig. 1, in the form of a lever 2 pivotted
at the lower end and carrying at the free or vibrating end in Fig. 1 a loop of
platina or other suitable material in constant electric circuit whereby it is rendered
incandescent. Such indicating device however may consist simply of a lever with
a point of strong color contrasting with the surrounding objects so that when the
lever is rapidly vibrating there will be represented to the eye a line or dash of
light or color of a length corresponding to the length of the vibration.
Opposite each diaphragm 1 is a sound collector 4 in the form of a tube of
suitable length preferably flaring at the outer end.
If a sound wave proceeds from an object directly in line with any one of the
indicators A it will strike the diaphragm of said indicator more directly and will
cause a greater vibration of said diaphragm than of those of the other indicators
and by observing in any manner, and preferably by recording the comparative
degrees of vibration the direction of the sound may thus be determined. If for
instance a sound is heard proceeding from any source and an examination of the
instrument shows that the diaphragm of the indicator at the right Fig. 1 is
vibrated to a greater extent than those of the other indicators it will at once be
known that the source of the sound is more nearly in line opposite the said
indicator than with the other indicators while if it should appear that the
diaphragm of the opposite indicator vibrates to the greatest extent it will at once
be known that the source of the sound is in the opposite direction.
If it should be seen that the diaphragms of two adjacent indicators vibrate to
about the same extent and to a greater degree than those of the other indicators
it will be known that the source of sound is at a point between and opposite the
said indicators whose diaphragms have the greatest vibrations.
In order however to insure a better indication it is desirable to multiply the
number of indicators using eight or more as will hereinafter be set forth or a
single indicator A Fig. 2, may be used capable of being turned or moved to
different points. This arrangement however is not so exact as the extent of the
vibrations at the different points cannot be simultaneously compared as in the
former case. The details of this figure will be hereinafter described.
Referring now to the construction of an operative instrument whereby the extent
of vibration of the different indicators may be visibly recorded Fig. 3 illustrates a
plan in which there are eight indicators, and Fig. 4 is an enlarged sectional
elevation of one of these indicators.
Each indicator is provided with a diaphragm 1 and an indicating device having
a recorder 3 carried by a lever 2 and a tubular sound collector 4 the lever 2 being
pivotted adjacent to the point of connection with the diaphragm so as to magnify
the movement of the recording end and the recorder consisting of a pencil which
rests upon a strip of paper 6 wound upon opposite parallel rollers 7 7 so as to travel
in a direction at right angles to the movement of the recorder.
As shown the various pairs of rollers are supported by brackets upon the
platform 8 of the instrument and a pinion 9 on the shaft of each roller gears with
an annular rack 10 which is caused to revolve by the action of any suitable motor

page_text: as for instance an electro-motor 13 carrying a worm upon its armature driving a
worm-wheel engaging with pins upon the underside of the annular rack 10.
Inasmuch as it is only necessary as a general thing to operate the indicator
occasionally means may be employed for throwing the motor into and out of
operation as occasion may demand for instance through the medium of a circuit
breaker 15.
So long as the diaphragms of the different recorders remain quiescent each
pencil 3 will indicate upon the travelling strip 6 a continuous comparatively straight
line but should any one or more of the diaphragms be vibrated an undulating line
will be produced the undulation being greater according to the extent to which
the diaphragms are vibrated and those diaphragms being vibrated to the greatest
extent in proportion to their direct exposure to the line of the sound waves and
facing the source of sound.
Thus, assuming that the sound waves move directly in the direction of the
arrow, Fig. 3, so as to act most directly upon the diaphragm of the indicator A¹
the undulating line produced upon the strip 6 of said indicator, will have deeper
undulations than those of the lines produced by any of the other indicators
thereby at once indicating to the observer the direction from which the sound
proceeds.
It will be evident that various means may be employed for recording the
indications other than the travelling strips for instance a disc 16, Fig. 5, may be
substituted for the various strips and when rotated under the different recorders
will be marked as illustrated or a single drum 17, Fig. 6, may receive upon its
periphery the marks made by one of the recorders, a sponge 18, serving to remove
each record after it has passed from sight leaving the surface clean for a subsequent
record. A more delicate recorder is illustrated in Fig. 7 in which each lever 2
bears upon a pin 18 projecting from the adjacent diaphragm 1 and is moved by the
latter in one direction and by a light spring 19 in the opposite direction and carries
a mirror 20 all the mirrors of the different indicators arranged to receive a light
from a central source as for instance a small incandescent lamp 21. Each mirror
is arranged at such an angle as to reflect a beam of light upward upon a sheet of
ground glass 22. So long as the diaphragms are not in vibration the reflection
from each mirror will remain as a single spot upon the glass but any vibration of
any diaphragm will rapidly move the corresponding mirror causing the reflected
light to appear as a line or dash.
By arranging the plate 22 at a considerable distance from the mirrors slight
differences in the vibration of the different diaphragms may be greatly magnified
so that it will be easy to distinguish at a glance the differences in the extent of
vibrations and consequently to determine the directions of the sources of sound.
In Fig. 8 we have illustrated one of the apparatus B consisting of a series of
eight indicators arranged near the bow of a vessel C in such exposed position as to
receive sound waves from different directions with but little interruption and
accessible for ready observation and in connection with said vessel there may be
arranged within the pilot house or other suitable place D, a receiving instrument E
so constructed as to record or duplicate the actions of the different diaphragms of
the instrument b so as to thereby prevent any mistake from inattention or error of
the look-out in charge of the instrument B.
The instrument may be constructed in any suitable manner to transmit the motions
of the several diaphragms of the instrument B to a movable portion of the
instrument E. Thus an electromagnet 23 may be arranged opposite the metallic
diaphragm 1 of each indicator as shown in Fig. 4 with the coils of said magnet in
connection with those of a magnet 24 of the instrument E as shown in Fig. 9 the
latter magnet operating upon the pivotted armature 25 carrying a mirror 26
receiving light from a lamp 27 and indicating its movements upon a sheet 28 of
ground glass in the same manner as in the apparatus illustrated in Fig. 7.
As each magnet of the instrument B is connected with a correspondingly
arranged magnet in the instrument E the movements of one armature will be

page_text: synchronous with those of the other so that there is a duplication of indications
while in many instances the indications within the pilot house may be depended
upon wholly without any observation of the instrument B.
In connection with two or more receivers within the pilot house or other suitable
location may be used two or more indicators stationed at different parts of the ship
so that one will receive the sound waves in advance of the other; the relation in
which such sound waves are received and the receiving instruments actuated
indicating the direction of the source of sound.
Such a receiver F is indicated in the pilot house D in Fig. 8 and in an enlarged
view Fig. 10.
In such receiver there are three receiving electro-magnets 24 similar to that
illustrated in Fig. 9 except that each armature is provided with a receiver 3 in the
form of a pencil all the recorders being upon the same line transverse to the direction
of movement of a sheet 46 which may be a travelling strip wound upon rollers 47
and provided with a series of parallel cross lines 48.
One of the receiving magnets for instance that marked 24ª is in electrical
connection with one of the magnets 23 Fig. 4 of one of the indicators of the
instrument B, another receiving magnet 24 is in connection with one of the magnets
of the indicator B' at the stern of the vessel while the central receiving magnet 24
is in like connection with one of the magnets of one of the indicators of an
instrument B about midships and as far as possible to one side of a line y passing
through the other two instruments B B¹.
By observing the differences in the times at which the different recorders 3 begin
their records upon the travelling sheets 26 the direction from which the sound
proceeds may at once be determined.
Inasmuch as there is an appreciable difference in distance between the different
instruments and any possible source of sound outside of a vessel of any considerable
length it will be evident that the sound waves will reach the different instruments
in succession, and if it be found that the instrument 24" begins its record in advance
of the others it will be known that the sound proceeds from a source forward of the
vessel while if the instrument 24° first begins its record the sound will proceed from
a source beyond the stern of the vessel, while if the record from the instrument 24°
is first made it will be known that the source of sound is at the right. In like
manner if the records of the two instruments 24ª, 24°, begin simultaneously preceding
that of the instrument 24b it will be known that the source of sound is at the left.
In the illustration afforded by Fig. 10 the record shows that the instrument 24*
has begun its operation first followed by 24" and then by 24° thus indicating
that the source of sound is ahead of the vessel.
By the use of a travelling strip with cross lines slight variations in the positions
of the undulations are rendered readily apparent to the eye so as to determine
the order in which such undulations have begun.
The sheet 46 may be of plain or ground glass with or without transverse lines
and instead of recorders the indications may be thrown on to the glass by mirrors
as before described.
While the above described instrument may be suitably mounted on any available
support we prefer to enclose the same completely excepting the outer faces of the
diaphragms within a circular casing 29 mounted upon a pedestal 30 Fig. 11 having
a central opening with a glass cover w which cover if desired may be the ground
glass sheet 22 Fig. 7.
By thus enclosing and covering the indicators the sound waves reach the
diaphragms only at the outer faces so as to avoid confusion in the action upon the
diaphragms that might otherwise result.
To cover the outer end of the collector tubes when the instrument is not in use
we employ a covering shield 40 vertically adjustable in any suitable way. For
instance it may have internal threads or inclines adapted to corresponding
bearings 41 on the casing 29 of the instrument so that by turning the shield it
may be raised or lowered.

page_text: In addition to the means heretofore described where the two instruments BB¹
are employed or in connection with such instruments without the instruments E and F
means may be used whereby the different angles at which the sound waves reach
the instruments B B₁ are ascertained and thereby an approximate estimate be
formed not only of the direction but the distance of the object from which the
sound proceeds.
Thus if by observing the instrument B it is found that the sound proceeds from
an object in a direction indicated by the line t, Fig. 8 and by observing the
instrument B' the indications show that the object is in a direction indicated by
the line the angles of these two lines being thus ascertained and the distance
between the instruments B B' being known the point of intersection of the lines t t¹
and distance of the object giving the sound may be estimated.
To avoid the necessity of communication between the different points of the
vessel and to facilitate comparison between the instruments each of the indicators
of the instrument B may be connected with the magnet of an instrument I, while
each of the indicators of the instrument B' may be connected with the magnet of the
instrument I the two instruments I I¹ being arranged in proximity within the pilot
house and the magnet of each instrument I I' being arranged in the same manner
as the indicators and each provided with an armature and mirror as in Fig. 9 or
being otherwise constructed so as to record the vibrations of the armature of the
magnet corresponding to those of the diaphragm with which it is electrically
connected.
In order to increase the intensity of the action of the armature and recorder in
any of the above described instruments we may produce variations in an electric
current by a microphonic action instead of depending upon variations in an induced
current. In such case the diaphragm 1 Fig. 12 bears upon a screw 35 and
conductors 36 37 connected with the diaphragm and screw have in circuit a battery
and the electro-magnet of the recorder 24 or other recording instrument.
In order to render more clearly apparent the indications of any recorder a lens 57
Fig. 6 may be arranged so as to magnify the indications.
When a single indicator is used as illustrated in Fig. 2 it may be connected
to a ring 5 which may be turned by hand or by gears like the ring 10 Fig. 4,
to different positions, and the arm 2 may be pivotted to a bracket upon the indicator
as shown at X Fig. 2 so as to be carried with the indicator or there may be a
series of arms 2 each pivotted to a stationary pin 21, the indicator diaphragm being
brought opposite each arm. To prolong the action of the diaphragm while the
indicator is at different points each arm 2 may bear upon a spring 53 against which
the diaphragm bears when sent to different points or a bar 54 may be carried by
the pivotted arm 2.
In connection with any of these devices any of the above described or other
recording means may be employed.
If desired the diaphragm may be placed horizontally with collector tubes con-
structed to direct the sound waves downward as shown in Fig. 13.
In the modification Fig. 14 a series of coils 90 are arranged upon a ring 95 each
coil being in circuit with a circuit breaker 91 and battery 92 and an indicator A
the diaphragm of the latter serving when situated to close the circuit and magnetize
the ring. According to the situation of the coil the polarity of the ring will vary
thus moving a pointer 93 to indicate the source of sound.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we wish it to be under-
stood that we do not limit ourselves to the use of the instruments herein set forth
or in said instruments to the special forms and arrangements of parts shown, but
what we do claim is
1. The method of determining the direction of sounds from a single point which
consists in receiving the sound waves at two or more different points and in
indicating the effects caused by such sound waves substantially as described.

page_text: 2. The method herein set forth of determining the direction of sound waves
which consists in indicating the varying action of sound waves from one point upon
indicating devices at different points substantially as set forth.
3. An instrument for indicating the direction oi sounds provided with two or
more diaphragms arranged in different positions with means for indicating
variations in the degree of movements of said diaphragms substantially as set
forth.
4. The mode described of determining the direction of sound by the use of two
or more diaphragms arranged to receive sounds directly from different directions
and means for visibly indicating variations in the effects produced on said
diaphragms substantially as set forth.
5. The method of determining the direction of sounds which consists in indicating
or visibly recording the effects of sound waves on one or more instruments con-
structed to be sensitive to such sound waves and placed in different positions sub-
stantially as set forth.
6. The method of determining the direction of sounds as herein described which
consists in receiving sound waves upon one or more instruments sensitive thereto
and set in different positions and indicating the effects thereof substantially as
described.
7. An instrument for indicating the direction of sounds provided with one or
more diaphragms arranged in different positions with means for visibly indicating
variations in the degrees of movement resulting at the different places substantially
as set forth.
8. An instrument for indicating the direction of sounds provided with two or
more diaphragms arranged in different positions with means for visibly indicating
variations in the degree of movement of said diaphragms substantially as set
forth.
9. The method of finding the distance of the source of sounds by means of
separated instruments indicating the angles of the sound waves substantially as
set forth.
10. The combination with an instrument provided with two or more diaphragms
arranged in different positions to be actuated to different degrees by sound waves
of a receiving instrument having electro-magnets each connected to be operated
electrically by one of said diaphragms and provided with recording means for
indicating the different movements of the armatures of said electro magnets sub-
stantially as and for the purpose set forth.
11. The combination with two or more indicators arranged in separated positions
and each provided with a diaphragm arranged to be operated by sound waves of a
corresponding number of electro-magnets arranged in proximity each connected
with one of the indicators for its armature to move synchronously with the
diaphragm thereof and recorders for indicating the order in which the different
armatures receive their impulses substantially as set forth.
12. The combination in an instrument for indicating the direction of sounds of
two or more diaphragms arranged to receive directly sounds proceeding from
different directions provided each with a marking device connected to be operated
by said diaphragm and a travelling sheet moving in contact with said marking
device substantially as set forth.
13. The combination with the series of indicators each provided with a recording
device and arranged in position for the different records to be simultaneously seen
and compared substantially as and for the purpose set forth.
14. The combination of two or more indicators sensitive to sound waves and
arranged in different positions and receiving and recording instrument connected
with all the indicators substantially as set forth.
15. The combination with the indicators arranged at separated points and with
corresponding receiving magnets and recorders operated thereby of a sheet 46 and
adapted to receive the several records substantially as described.
16. The combination with the indicators arranged at separated points and with

page_text: corresponding receiving magnets and recorders operated thereby of a sheet 46
provided with transverse lines and adapted to receive the several records substan-
tially as described.
17. The combination with a vessel of two instruments B B' arranged in different
positions each instrument provided with a series of devices sensitive to the action
of sound waves from different directions substantially as set forth.
18. The combination with a vessel of two or more instruments B B¹ each
provided with a series of diaphragms and means for recording the actions thereof
under the influence of sound waves and recorders at a central point connected with
the different indicators to operate synchronously therewith substantially as set
forth.
19. The combination of a series of indicators arranged radially and each provided
with a diaphragm adapted to be operated by sound waves of recording devices
connected with the diaphragm substantially as set forth.
20. The combination with a series of indicators each provided with a diaphragm
adapted to be operated by sound waves of a corresponding series of recording
devices arranged at a distant point and each connected electrically with one of the
diaphragms to move therewith substantially as described.
21. The combination with a series of diaphragms and indicators adapted to be
actuated by sound waves of mirrors connected to be moved by said diaphragms and
a lamp arranged in position for its rays to fall upon the mirrors substantially as set
forth.
22. The combination of a series of indicators arranged radially and each provided
with a diaphragm adapted to be operated by sound waves of a series of visual
recorders each connected to be operated by one of the diaphragms substantially
as and for the purpose set forth.
23. The combination with a series of recording devices of a single indicator and
means for adjusting the indicator to different positions to operate the different
recorders substantially as set forth.
Dated this 17th day of March 1891.
W. P. THOMPSON & BOULT,
Agents for the Applicants.