Improvements in Means or Apparatus for Recording and Reproducing Speech and other Sounds."
Year: 1898

page_text: Date of Application, 12th Dec., 1898- Accepted, 11th Mar., 1899
יעטע.
Improvements in Means or Apparatus for Recording and
Reproducing Speech and other Sounds."
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields, in the County of London
Gentleman do hereby declare the nature of this invention (which has been
communicated to me from abroad by the American Graphophone Company, a.,
Corporation organised under the Laws of the State of West Virginia, United States
of America and having its principal place of business in Washington, District of
Columbia, United States of America) 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 the art of recording and reproducing sounds, and its object
is to obtain complete and accurate records and reproductions of articulate speech and
all other sounds, practically the same in volume and tone-colour, or quality, as the
original sounds.
It has long been realised by those conversant with such matters that the best
reproductions of sound obtained by means now in general use, besides being very
small in volume compared with the original sounds, differ therefrom in character to a
greater, or lesser degree. These differences have been recognised as of two principal
sorts, first, the absence of components characterizing the original sounds (especially
noticeable in closed sounds, aspirates, sibillants, and high pitched sounds) and second
the presence of foreign sounds, or characters. The latter difficulty has been attributed
to various causes, generally to so-called "false vibrations," but after every effort to
overcome these difficulties, and to eliminate false vibrations, the characteristic
differences stated above, distinguishing the reproduced, from the original, sounds.
still remained very strongly marked.
The complete result of sound reproduction involves two operations; first, the
making of the record, and second, the reproducing of the recorded sound. The
theoretical object is to cause the reproducing diaphragm, or vibratory member, to
copy exactly the movements of the recording diaphragm. If this be done with
mathematical exactness the reproduced sounds will be identical with the original
sounds. Failure to attain this result may obviously be due either to failure of the
recording style, or failure to make a groove which is an exact graphic representation
of the sonorous vibrations, or to a failure of the reproducing style to follow exactly all
the irregularities of the groove so as to perform all the movements corresponding
thereto, and none other.
The imperfection of the results hitherto attained is due, in fact, to both these

page_text: causes, and the purpose of this invention, briefly stated, is to obtain accurate and
complete representations, in the form of a sound-groove, of al! sonorous vibrations,
and to cause the reproducing diaphragm to vibrate strictly in accordance with the
said record, and thus copy, in amplitude and character, the motions of the recording
diaphragm.
It is difficult to make a close aud accurate observation of what actually takes place
in recording and reproducing sounds because the movements, although of very com-
plex character, are seldom more than two-thousandths of an inch in amplitude, and
are at the rate of hundreds of complete vibrations per second. By the aid of theory and
careful microscopical investigations, it has been possible to determine these operations
with precision.
1
In making a record, an important factor is the resistance of the recording medium
to the movements of the style. To obtain the utmost freedom for the movements of
the style, and the maximum cutting effect, the axis of the style should be placed at
as small an angle as practicable with the tangent of the cylindrical tablet (when that
form is employed), at the point of contact, the smaller this angle, the smaller being
the resistance of the material to the cutting edge of the style. In practice the best
results have heretofore been obtained when this angle is somewhat less than 35 degrees,
it not being practical to make it much less. Under these conditions what occurs is
that when the style begins to move into the recording material to cut a depression
the heel of the cutter (that is the portion behind the cutting edge) comes into
contact with the crest that is being formed and checks the penetration of the
style. Obviously the more the style is inclined towards the tangent the more effec-
tive is the check thus imposed on the movement of the style. Consequently, the
the style will begin to descend in accordance with the characteristic acoustic vibra-
tion at the instant impressed on the diaphragm, but will begin to depart from the
characteristic movement as soon as the checking influence is felt, and will depart from
it altogether as soon as the resistance overcomes the force of the vibration, which is
exceedingly feeble. A further consequence follows from the fact that the vibration of
the diaphragm is pendulous in character, and, like the strings of a musical instrument,
when perfectly unrestrained, moves in a full vibration the same distance to one side
as to the other of its normal position. But again, like the strings of an instrument,
the diaphragm if checked, or damped, on one side of the medial line, will be unable
to perform its proper movement, either in amplitude, or character, on the other side
of that line.
Consequently, from the cause above stated, the ascending, as well as the descending
movement of the style is altered from what it would be if perfectly free to follow the
movements of the air particles acting on the diaphragm. The departures are, of
course, more strongly marked as the complexity of the sound increases, being least
noticeable with a simple rythmical vibration like that of a tuning fork.
The record thus produced will accordingly correspond at parts inore, or less, closely
to the form of the sonorous vibrations, and at other parts will cease to correspond,
and these corresponding and diverse parts will alternate at short intervals so that a
general correspondence to the more prominent features of the sound will be
preserved.
The record thus produced, studied microscopically, is characterized by short, abrupt
curves and crests, or elevations, close together. Necessarily, even if the reproducing
stylus could be caused to follow such a record with perfect accuracy the reproduced
sound would not correspond, either in volume, or character, with the original. But
at this point another difficulty appears. The end of the rubbing reproducing style
must have a certain minimum diameter, and an approximately spherical curvature,
in order that it may not injure the record. Such a style cannot enter into all the
depressions of the record, and furthermore, the abruptness of the cam-like action of
the successive elevations imparts a blow, rather than a gradual, controlled movement
to the stylus which often throws it off the record, some material portion of which
passes before the stylus again makes contact with it.
Another, and in some respects more serious, defect existing to a greater, or lesser;

page_text: 'degree in all sound records beretofore made, is that they do not embody an accurate
record of the more minute vibrations which give to sounds their tone-colour, or
quality. These vibrations are exceedingly feeble and the resistance offered by the
record material to the recording stylus, (together with the other causes above referred
to as modifying the record of the more prominent sonorous vibrations,) frequently
overcoines the minute vibrations mentioned so that they are not recorded at all, or if
recorded, they become much modified in character.
The present invention involves a principle which may be briefly stated as follows:
If the speed of the record tablet he sufficiently great the crest of the last formed
undulation may be withdrawn from under the recording style so quickly that the
heel of the latter will at no time come into contact with such undulation, and the
amplitude of vibration of the recording diaphragm, to both sides of its medial position,
will not be checked, or damped, thereby, and the recording stylus will thus be enabled
to cut a record groove whose undulations correspond with accuracy to the sonorous
vibrations to be recorded. It has been found that a surface speed for the tablet of
about 44 meters per minute gives very satisfactory results. It is obvious, however,
that such speed may be varied within certain limits, depending somewhat upon the
angle at which the recording stylus is placed with relation to the tablet, and the
character of the sounds to be recorded. When moving the tablet surface with a speed
of about 44 meters per minute, it is possible to place the axis of the recording style
much more nearly in line with a tangent to the cylindrical tablet at the point of
contact than bas heretofore been found feasible in the method of recording in which
the surface speed of the tablet was so slow as to permit the heel of the style to come
into contact with the crest of the undulation.
Figure 1 of the accompanying drawings shews a recorder with the cutting edge of
its stylus embedded in the surface of a cylindrical tablet, the axis of the stylus being
at an angle of about 20 degrees to a tangent of the cylinder at the point of contact:
Figure 2-is-n-planwiew of one-form-of-recorder,-employed
Figure-3-is-a-plan of a blank-for-a-clamp-for-the-recording stylus
Figure 4 is a diagram shewing the manner in which the vibrations of the recording
diaphragm are damped in the method heretofore employed by reason of the undula-.
tions making contact with the heel of the stylus :
Figures 5 and 6 are views of the undulations in the bottom of a record made by the
method of the present invention as the same are seen under the microscope.
Figures 7 and 8 are views of the undulations in the bottom of a record made by the.
old method, as seen under the microscope.
The undulations in Figures 5 and 7 and in Figures 6 and 8, respectively, are from
the same sound, recorded at the same time and magnified to the same degree.
Referring to Figure 1: A represents a suitable record tablet mounted to revolve in
the direction indicated by the arrow, and B is a recorder having its cutting style E..
embedded in the tablet in the act of forming the recoril undulations y. Any suitable
form of recorder may be employed: but-the-recorder-shewn-is-one-of-novel-construc-
tion-which-can-be-used-in-the-formation-of-records-necording-to-the-novel-method
herein-described.
employed,
The-main-portion-or "head" of the recorder-is-of-the-general-form-commonly
having-the-passage-way-a-from-the-centre-of-the-fut surface-of-the-headt
through-the-rear-end-thereof.-B-indientes-a-ring-of-yielding material, preferably
rubber is the diaphragm:-D-is-the-arm, or lever, earrying the entting point-B,
und-attached-at-one-end-to-the-margm-of-the diaphragm,-at-d-and-at-the-other-end
to-the-centre-of-the-diaphragm, opposite to the entrance of the passage-way-u-at
d-d
The ring B is attached by cement-to-the-margin-of-the-flat-surface of the heads.
after-which-the-diaphragm is placed lightly upon the ring and allowed-to-settle
down into place by its own weight. This entirely prevents any strain, or-twisting
whatever
The-blank-shown in Figure 3 is formed into a tube, clamped firmly around the
cutting point at the end containing the flanges; the flanges are bent-down, and

page_text: their
may, if desired,-be-bent downward-slightly-at-d"-co-as-to-present-the-stylus-to-the
blank-eylinder-at-the-proper-angle;-herein shewn-as-about-20-degrees from-a-tan-
gent-at-the-point of contact. And, finally, the-arm
extremities--bent--outward--to--form--feet-d'--d':-The-arm-D-thus-formed
D-is-cemented-to-the-diaphragm
at-d'-d' as described. As-the-arm-D-is-attached-to-the-diaphragm-at-both-ends,
the-feet-d¹-d¹-may-be-far-smaller-than-if-they-were-the only means-of-attachment.
This-presents-the-two-fold-advantage of not interfering-with-the-buckling action-of
the-diaphragm,-when-in-vibration-and-of-not-acting-as-a-damper.
The advantages of the recorder are that the diaphragm-has-fuller--and--freer
vibrations, and-is-not so liable-to-break;--that-the-cutting point-has-a-greater-range
of vibration,-more-nearly-at-right-angles to the diaphragm,-und-more-nearly normal
to the surface of the blank cylinder; and that--the-recorder-as-a-whole, besides
being simpler--and--cheaper;--is--far-lighter,--which--is-recognised--as------great
desideratum.
In making sound records according to the method of the present invention the
point of the recording style is slightly embedded in the surface of the tablet and the
said tablet is rotated at such a surface speed as to leave the diaphragui perfectly free
to give its full vibration in response to sonorous vibrations impinging thereon without
any contact between the crests of the undulations and the heel of the cutting style:
Obviously the rate of surface speed for the tablet which is necessary to accomplish
this result will depend, to a certain extent at least, upon the angle at which the
recording style makes contact with the record tablet. The invention may be practiced
with a flat, or a cylindrical, tablet, as desired and when the latter form is employed
the style may if preferred, be placed at an angle of 30° to a tangent to the cylinder
at the point where the style makes contact therewith. In the practical formation of
sound records according to the methods heretofore used this has been deemed the most
feasible angle. A stylus placed at about this angle is shewn in the diaphragm of
Figure 4. In this figure the undulations which would be formed by the stylus, if the
record surface were moved at the speed heretofore employed is indicated by full lines.
In practice these undulations are found to be short, close together and abrupt in
character, and, as the cutting edge of the stylus descends into the depression succeeding
each undulation, it moves freely in response to the vibration of the diaphragm until
the heel of the stylus makes contact with the crest of the undulation, as shewn in
Fig. 4, whereupon the cutter ceases to penetrate, and the vibration is lost. The depth
to which the depression would have been cut had not the stylus been checked by
contact with the crest of the undulation is indicated by dotted lines under each
depression. But this does not represent all the loss to the height of the undula-
tions, for by damping the swing of the diaphragm in its downward direction, its
reactionary swing to the opposite side of its medial position is checked, or
lessened, to a practically equal amount, so that the loss is on the crest of the undula-
tion as well as in the depression. Were the diaphragm and stylus free to make their
full swing without any damping effect due to the contact of the style with crests of
the undulations, the crests of the latter and the depressions, or valleys, between thein
would be represented by the dotted lines of Fig. 4. It will he apparent from this
diagrammatic illustration that the amplitude of vibration imparted to the repro-
ducing diaphragm by the undulations of a record as heretofore formed must, of
necessity, be much less than that imparted to the recording diaphragm by the
original sounds, and that therefore the reprcduced sounds will not be nearly so
loud as the originals. In the practical making of sound records prior to the present
invention the record tablets have usually been in the form of cylinders of wax-like
material about one half decimeter in diameter revolving but slightly under, or above,
110 revolutions per minute, giving a surface speed to the tablet of about 170 deci-
meters per minute in round numbers. With this surface speed the damping effect
due to the contact of the crests of the undulations with the heel of the recording
stylus has been invariably experienced and the reproduced sounds have not been
nearly so loud as were the original sounds. By the present invention the surface
speed of the tablet is so great as to give the revolving diaphragun perfect freedom
-

page_text: of vibration without any damping effect due to the contact of the undulation with
the heel of the stylus. The requisite surface speed might be attained by increasing
the number of revolutions per minute given to cylinders one half decimeter in
diameter, or thereabouts as hitherto employed. There are practical o jections to
this, however, and it is therefore preferable to drive the cylindrical tablet at the same
number of revolutions, viz., about 110 per minute, and to so increase the diameter of
the tablet as to secure the requisite surface speed, and it has been found that a
cylinder about one and one-fourth (1·25) decimeter in diameter will attain a sufficient
surface speed when rotated at the speed mentioned. Obviously the same results can
be obtained by increasing the Dumber of revolutions and making the diameter less
than one and one-fourth (1·25) decimeters, or by increasing the number of revolu-
tions and increasing the diameter of the tablet; and such changes would come
within the.scope of this invention, the essential feature of which is that the surface
speed must be such as to withdraw the undulation from under the heel of the recording
style without contact therewith.
In Fig. 1 is shewn a tablet which is preferably about one and one-quarter decimeters
in diameter and, when practicing the method of the present invention, is given
approximately 110 revolutions per minute, thereby attaining a surface speed of about
fourty-four (44) meters per minute. By giving the tablet this surface speed and
causing sonorous vibrations to impinge upon the diaphragm of a recorder whose
stylus is in. contact with the surface of the tablet, a record groove will be formed
therein having undulations with long, gentle, easy slopes as distinguished from the
short, abrupt undulations heretofore formed. The general character of the record
groove thus formed is indicated in an exagerated degree by the wavy line y to the
right of the recording stylus in Fig. 1. This is not intended to be an accurate repre-
sentation of actual undulations corresponding to sound waves, but in Figs. 5 and 6
are seen representations of the undulations corresponding to the syllables "sol"
and "do" respectively, when sung by a baritone voice at about the middle register,
as such undulations appear when seen under the microscope. In Fig. 7 are repre-
sented the undulations of a record groove corresponding to the syllable "sol
when sung by a baritone voice and seen under a microscope, when the same is
recorded by the method used prior to the present invention, that is to say, by
imparting to the tablet-surface a speed of about 175 decimeters per minute; while
in Fig. 8 is represented the undulations corresponding to the syllable "do," likewise
made by the old method, by a baritone voice and magnified.
17
It is to be understood that the records whose undulations are represented in
Figs. 5 and 7 were made simultaneously from the same voice sounding the same
syllable, the undulations being subsequently magnified the same number of
diameters, and the same is true of the undulations reproduced in Figs. 6 and 8.
It will be seen that the undulations of Figs. 5 and 6, made by the method of the
present invention, have long, gentle, easy slopes as distinguished from the undulations
of Figs. 7 and 8, made by the old method, which have short, abrupt, curves.
Referring again to Fig. 1, in connection with Figs. 5 and 6, it will be seen that, by
reason of the long, gentle, easy slopes of the undulations, the heel of the stylus wili
not, at any time, make contact with the crest of the recording undulation.
result of this, three highly important advantages are secured.
As a
First, the amplitude of the undulations is greatly increased, that is the height of
the undulations from the crests thereof to the bottom of the intermediate depressions
is much greater; the vibrations of the diaphragm and stylus are not checked, or
damped, and therefore the crests of the undulations in the record, as well as the
depressions between them, will accurately correspond to the full swing of the recording
diaphragm in both directions. This will cause the record to impart, to the repro-
ducing diaphragm, vibrations equal in amplitude to those impressed upon the
recording diaphragm by the recorded sounds and the reproduced sounds will
5 therefore be approximately as loud as the sounds originally recorded.
Second, the angle between the axis. of the recording stylus and the tangent to the
cylinder at the point of contact, with the stylus need not be more than 20 degrees.

page_text: This is approaching very nearly to the theoretical line of least resistance for the
stylus, which line is along the said tangent; and
Third, the undulations will accurately correspond to the vibrations of the recorded
sound waves, without distorting the larger and stronger ones, and without distorting.
or suppressing, the more minute and feeble ones. Since the heel of the stylus does
not make contact with the undulations, the stylus will be free to cut the undulation
in exact response to the action of the stronger sound waves without distortion ;
This-will-be-readily understood-in-connection-with-the--explanation, herein before
given, of Fig; and the decreased resistance, due both to this and. to the advan-
tageous angie for the cutting style, enables the feeble and minute undulations, to
which tone-colour, or quality, is due, to more effectively impress themselves upon the.
style and, through it, upon the record. The increased velocity at which the record
tablet moves also decreases the resistance to the cutting action of the style.
In addition to the advantages thus secured in the formation of the tablet or record,
greatly improved results are secured when reproducing from the record thus formed.
The long, gentle, easy, slopes of the record act in an even, yet forceful, manner on
the rubbing style of the reproducer and thereby impart to the reproducing diaphragm
smooth, but positive, vibrations exactly corresponding with the undulations of the
record. Owing to the entire absence of short, abrupt curves in the record no blows
are struck by the undulations upon the rubbing style and the foreign vibrations,
hitherto caused thereby, are therefore absent from the reproduced sounds. Further-
more, the rubbing style will, on account of the long, gentle, slopes, remain, at. all
times, in contact with the undulations of the record, and will neither skip over the
crests, nor across the sharp depressions between the crests, so that the vibrations of
the reproducing diaphragm will be, at all times, in exact accord with the undulations
of the record.
In short by means of the present invention a record corresponding in character and
extent to the sonorous vibrations is secured, which record positively imparts to the
reproducing diaphragm vibrations like, in character and extent, to those of the
recording diaphragm. The result of this is that the reproduced sounds will be of
equal loudness and purity with the original sounds, and will possess all those char-
acteristics to which tone-colour, or quality, are due.
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 :-
1. Forming a sound record by placing a vibratory recording style in contact with
a record tablet and simultaneously impressing sonorous vibrations upon the style
and imparting,movement to the tablet with a surface speed sufficient to cause the
style to form in the tablet undulations with long, gentle, slopes as distinguished from
short, abrupt, undulations, substantially as herein before described.
2. Forming a-sound-record-by-placing-a-vibratory-cutting-style-in-contact-with-e
record-tablet, impressing conerous-vibrations-upon-the-style, and-simultaneously
moving-the-tablet, relatively to the style, with a surface-speed-sufficient-to-prevent
the-heel-of-the-style-from-coming-into-contact-with-the-undulations, substantially
as hereinbefore-described.
2 Formning a sound record by placing a vibratory cutting style in contact with
a wax, or wax-like, record tablet, and simultaneously impressing sonorous vibrations
upon the style and moving the tablet with a minimum surface speed of about 44 meters
per minute, substantially as herein before described.
4.The method-of-forming a sound-record-substantially as herein before-described
and illustrated in the accompanying drawings..
35: A sound record having the record groove. formed with undulations having
long, gentle, easy, slopes, as distinguished from short, abrupt, undulations, sub-
stantially as herein before described.
46. A sound record having the record groove cut, or engraved, in a tablet of wax,
r wax-like inaterial, the undulations of the record having long, gentle, easy, slopes.

page_text: as distinguished from short, abrupt, undulations, substantially as herein before
described.
7. The sound-record formed by engraving, substantially-as-hereinbefore-described,
and-illustrated-in-the-accompanying-drawings, the-said-record-corresponding in
amplitude-and-character,-to-the vibrations of the-sound-ware.
A-sound-recorder-comprising-n-hend;-or-support-a-diaphragm-seenred-at-the
edge-of-one-of-its-sides-to the said head, or support, but unattached-on-its-opposite
side;-and-a-recording-stylus-attached-to-the-suid-diaphragm, substantially as herein-
before-described.
0.
side to
and a
A sound-recorder-comprising-a-head-or-support-a-diaphragm,-a-stylus,
ring-of-yielding-material-cemented on one-side to the-said-head, and on the other
the edge-of-the-said-diaphragm,-substantially-as-hereinbefore-described.
10. A sound-recorder-constructed--and--operating substantially as hereinbefore
described-and-illustrated-by-the-accompanying-drawings:
3000
JOHNSONS & WILLCOX
47 Lincolns Inn Fields London W.C. Agents