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Патент USA US2107135

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Feb. 1, 1938.
W. WILSON
2,107,135 '
MEANS FOR NEUTRALIZING SOUND DISTORTION
Original Filed April 24, 1923
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' 2,107,135
‘MEANS FOR NEUTRALIZING SOUND DISTORTION '
Original Filed April '24, 1929
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2,107,135
Patented Feb. 1, 1938
UNITED STATES PATENT OFFEQE
2,107,135
MEANS FOR NEUTRALIZING SOUND DIS
TOR-TION
_Wesley Wilson, Chicago, Iii.
Application April 24, 1929, Serial No. 357,861
Renewed August 13, 1937
9 Claims’. (Cl. 179—-100.3)
My invention relates to translating devices duced apparatus counteracts the effect of the dis
(such as electrical sound reproducers, trans
tortion produced by said part.
It will be understood that the following de
scription relates more to this example of the
practice of the invention and that the invention
will be de?ned in the appended claims.
This invention is particularly adaptable to elec
Further objects will appear from the descrip
trical circuits and energy transformers of sound 7
formers, microphones, light control valves, etc.)
and more particularly it contemplates the coun
5 teraction of distortion arising therein.
recording and reproducing apparatus in which
the permanent record is made on photographic
10 ?lm.
These ?lm records can be so made as to
tend to counteract distortion arising within the
recording and reproducing apparatus.
This is
not only an advantage in reducing distortion
which can not be overcome by the methods of
15 construction in vogue but also where a saving or
simpli?cation in the construction of the appara
tus would be effected if it were not necessary to
_
In the drawings, in which several embodiments
Figure 1 is a diagrammatic view showing ap
paratus for making a sound record on photo
graphic ?lm and counteracting the e?ect of the
distorting characteristics of the reproducing and
recording apparatus;
Fig. 2 is a face View of a portion of the photo
graphic ?lm showing diagrammatically the direct
sound record and the counteracting sound rec
This invention is also adaptable to radio broad
casting and television, in which case the electrical
ord;
Fig. 3 is a view similar to Fig. 2 but showing 4
impulses or waves could be distorted reversely at
diagrammatically a different type of sound rec
the broadcasting station to the distortion arising
ord;
Another possible method of utilizing this in
vention is in secret communication such as te
lephony and the transmission of pictures by
radio. In this method it would be necessary to
arti?cially cause distortion in the receiving ap
paratus to such an extent that the reverse dis
SO vtortion
necessary in the sending apparatus (to
counteract the distortion in the receiving appara
tus) would be so great that the signal would be
unintelligible if reproduced on apparatus not
having the proper distortion.
Among the objects of my invention are to re
duce the degree of distortion arising within
translating devices by distorting the electrical
waves (which operate or are operated by said
devices) in the reverse direction to the distortion
produced in the waves by the translating device;
to tend to neutralize the distortion arising vwith
in sound or picture recording and reproducing
apparatus by deliberately distorting the records
(which are made and reproduced by this appara
' tus) in the reverse direction to the distortion
arising within said apparatus.
A further object of my invention is to provide a
method of correcting the effect of distorting char
acteristics in part of a sound controlling appara
‘ tus, comprising the introduction into the sound
10
of my invention are shown—
reproduce the record with perfect ?delity.
within the reproducing apparatus.
40
tion and claims.
Fig. 4 is a view showing diagrammatically the
manner in which the two sound records of Fig. 2
may be combined in a single record at the side 25
of the ?lm;
Fig. 5 is a face view showing diagrammatically
how the two sound records of Fig. 3 may be com
bined in a single record, at the side of the ?lm;
Fig. 6 is a diagrammatic view showing appara
tus for reproducing the sound from photographic
?lm similar to that shown in Figs. 2 and 3;
Fig. '7 is a diagrammatic view showing appara
tus for counteracting at the broadcasting station
the e?ect of distorting characteristics in the
audiofrequency ampli?er system of a radio re
ceiving set;
Fig. 8 shows apparatus for counteracting the
eifect of distorting characteristics in‘ amplifying
and reproducing apparatus in which the counter
action or reverse distortion is effected electri
cally;
.
Fig. 9 shows apparatus for counteracting the
effect of distortion arising within a loud speaker
in which the reverse distortion is effected by
energy dissipation; and
Fig. 10 is a chart showing curves plotted from
the table at the end of the speci?cation.
'
The basic idea underlying the various form of
my invention shown is a method of correcting -
the effect of distortion arising within translating
controlling apparatus of additional apparatus
devices (such as electrical sound reproducers,
having distorting characteristics similar to ‘the
distorting characteristics of said part in such
manner that the distortion caused by the intro
transformers, microphones, light control valves,
etc.) by utilizing additional apparatus having ap
proximately the same distorting characteristics
2
2,107,135
as the device producing the objectionable distor
tion, in such a manner that the distortion caused
by he introduced apparatus will have a counter
acting eifect with respect to the objectionable dis
tortion. For example, if a ?lm record is made ofa
violin solo by recording apparatus which produces
distortion in the record in varying degrees and at
certain de?nite frequencies itis obvious that this
distortion will be reproduced in the reproducing
10 apparatus. Now, if there is distortion. also in
the reproducing apparatus it is also obvious that
this distortion will also show up in the reproduced
violin solo. That is, there will be a variation in
torted the most will have the greatest difference
between their equivalent value on the primary
and secondary records.
If the notes or frequen
cies recorded on the secondary record are made
to partially neutralize the corresponding notes
on the primary record and the resultant effect
recorded on a third ?lm it will be found that this
third ?lmwill be distorted in the proper direction
to at least partially neutralize the effect of distor
tion arising within the said apparatus. By 10
varying the degrees of neutralization between the
original (primary) and secondary record when
solo that is reproduced from the ?lm record. If
this same recording apparatus is used to make a
making the neutralizing record, it is possible to ob
tain the most advantageous degree of neutraliz
ing distortion. Bearing in mind that the equiva
lent value of corresponding notes on the primary
(original) and secondary records are identical
record of the sound that is reproduced by passing
the original record through the reproducing ap
when there is no distortion in the apparatus it
becomes apparent that the notes that will be
the equivalent value of the corresponding notes
or frequencies in the original violin solo and the
20 paratus, it is obvious that in this second record,
which we will call the secondary record, the equiv;
alent value of the notes will vary from the cor
responding notes in the original record at all
points where there was distortion in the reproduc
25 ing apparatus or in the recording apparatus as
it was making the secondary record,
If in either the reproducing or recording ap
paratus the ,e?iciency is very low when handling
notes of one particular frequencyv it will result in
30 the recording of this note on the secondary record
at an equivalent value below that of the original
record. Now, if the e?iciency at this frequency
was, lowered in the recording apparatus it would
mean that the equivalent value of the note on
i the original record would be lowered by this dis
tortion and would again be lowered on the sec
ondary record.
If all of the distortion were in
the reproducing apparatus at this frequency it
would me'anthat on the original record this note
neutralized the most will be the ones that were 20
weakened the least by distortion within the said
apparatus. In actual practice this method is
quite impractical and is of value only as a means
of explaining the theory of the invention: In
stead the electrical waves from the pick-up 25
apparatus receiving the original sound waves are
divided and made to flow through two parallel
channels. One is provided with additional ap
paratus for producing distortion similar to the
objectionable distortion and controls alight .
valve. The other channel also controls a light
valve but has no additional apparatus for de
liberately producing distortion.
(This is similar‘ ~
to the system shown in Fig. l of the drawings.)
The light ?uctuations from these valves are re- .
corded on the same ?lm, either side by side (as
shown in Figs. 2 and 3) so as to make two sepa-.
rate records (which would correspond to the
40 would not have its equivalent value lowered but
original and secondary ?lm records and‘ which
could be made to partially neutralize each other
would be lowered on the secondary record.v
Therefore, in either case the equivalent difference
between the two records would depend upon the
distortion in ‘the reproducing apparatus‘ or in the
in the reproducing apparatus as. in Fig.6)v or
the two records could be superimposed (as shown.
in Figs. 4 and 5) if care were. taken to insure that
the recorded light from one valve neutralized the
‘ recording apparatus when recording the sec
ondary record. Or another way of saying it is
that the equivalent differences between corre-,
sponding notes on the original and secondary rec
ords are similar to the equivalent differences be
tween the notes of the original violin solo and the
corresponding notes of the reproduced solo. Now,
a way to neutralize this effect of distortion arising
within the recording and reproducing apparatus
is to distort the ?lm record in the reverse direc
,, tion to the distortion arising within said ap
paratus' That is, if the equivalent value of a
particular note or frequency is lowered by distor
tion in either the recording or reproducing ap
paratus the ?lm record should have this note
recorded at a higher‘ equivalent value in order to
neutralize it. As the distortion recorded on the
original and secondary records is in the same
direction (but in different degrees) as the distor
tion arising within said apparatus, it follows that
(3.“ the desired ?lm record (which will be called the
neutralized record) should be distorted reversely
to the distortion in the, original and'secondary
record.
'
Now, as the equivalent value of notes on the
secondary record have been lowered below the
sound reproducing quality of the recorded light
from the other valve,‘ to such an extent as to
produce the proper degree of reverse distortion.
The electrical waves from the two channels
can be made to partially neutralize each other
direct (as shown in Fig. 8) if a means is provided’ _
for maintaining the time lags in the channels
identical. Such an arrangement would'be adapt
able to public address systems, radio telephony;
the making of wax records for phonograph re
production,
etc.
.
.
-
,
Referring to the drawings in detail, and ?rst
to the apparatus shown in Figs. 1 to 3, inclusive,
this comprises in general, apparatus'for produc
ing sound records on photographic ?lms, which
?lms, after having the sound record made there
55
on, may thereafter be used in the sound reproduc
ing apparatus in Fig. 6. The apparatus shown in
Fig. 1 comprises sound pickup which may be‘ of
any usual or suitable type, including input means
I and, amplifying means 2, a light control ap 65
paratus 3 controlled by the microphone, for pro
ducing a sound-record onrthe ?lm 4 correspond
ing to the received sound, and a corrective circuit
for counteracting the effect of the distorting char
equivalent value of corresponding notes on the
original record to the extent resulting from dis
acteristics of the apparatus shown in Fig‘. 6 and 70
also input I and ampli?er 2. It is well known
that reproducing apparatus, such 'as shown in
tortion caused by passing once through the re
producing and recording apparatus it follows
that notes or frequencies which have been dis
Fig. 6, almost necessarily possesses distorting
characteristics which will distort certain portions
of the sound record more than it will‘ distort 75
3
2,107,135
other portions; that is to say, certain frequencies
may be reproduced well and with little loss of
volume, while other frequencies may be repro
duced poorly; that is, with considerable loss of
CL volume. It is with a view to equalizing this dis
tortion or loss of volume that the present ap
paratus is designed. In order to effect this equal
izing or counteracting effect, certain apparatus is
introduced into the recording apparatus of Fig.
10 1, including an ampli?er 5 and speaker 6 (which
should be identical with or similar to the arm
pli?er ‘l and speaker 8 of the apparatus of Fig.
6), receiving means 9 for sound transmitted by
the speaker 6, which should have characteristics
similar to input i, amplifying means II! (which
should be similar to 2) for the receiver 9, and
light control apparatus H for causing a sound
record to be made on photographic ?lm 4 which
can be made to correct the effect of distortion
due to the distorting characteristics of the re
producing apparatus of Fig. 6, and also input I
and ampli?er 2 of Fig. 1.
In order to take care of the time lag caused
by the fact that the receiver 9 is necessarily
placed an appreciable distance from the speaker
6, the recording point A2 of the light control ap
paratus I! of the corrective circuit may be ad—
vanced a slight distance in the direction of ?lm
movement from the recording point I?» of the
light control apparatus 3 of the direct circuit,
the distance “A” having such a relation to the
distance “B” that it will counteract the time
lag due to the spacing between the receiver 9 and
the speaker 6.
Bearing in mind that the ampli?er 5 and
speaker B of the corrective circuit have distort
ing characteristics substantially the same as the
distorting characteristics of the ampli?er l and
speaker 8 of the reproducing apparatus of Fig. 6
40 and that the receiver 9 and ampli?er ID of Fig. 1
are similar to the input means I and ampli?er
2 of Fig. 1, and also that the record made from
light control 3 will correspond to the direct (pri
mary) record, while the record made from light
control II will correspond to the secondary rec
ord (which will be recorded in opposite phase).
Recording in opposite phase may be accomplished
by reversing the electrical connections, as shown
clearly in Figs. 7, 8, and 9. Fig. 1 has a re
versed connection between receiver 9 and am
pli?er ID in that the upper conductor becomes
the lower conductor on making the bend. It will
be seen that there can be effected a partial neu
tralization of the direct record by the secondary
record by properly adjusting light sources 25 and
26 of Fig. 6 which will produce the counteracting
(reverse distorting) e?ect. Thus those parts of
the record which would otherwise be reproduced
with too great a volume will have this volume
automatically cut down by the corrective circuit
to a considerable extent, while those parts of the
record which are relatively poorly reproduced in
the apparatus of Fig. 6 will have their volume cut
down comparatively little, by the corrective cir
cuit of Fig. 1. By recording these two records
on the same ?lm no trouble should be encoun
tered in permanently maintaining them in the
proper phase relation.
If recorded on separate
recording medium this would be practically im
70 possible to do. If the primary and the second
ary records are made side-by-side, either as a
variable density record as shown in Fig. 2, or as
the variable width method as shown in Fig. 3,
it will not be necessary to accurately control the
75 relative intensities at which the two records are
recorded. All that is necessary is that the two
records be 180° out of phase.
Fig. 2 shows one type of ?lm record (known
as the variable density type) which might be
made by the apparatus shown in Fig. 1. The
direct primary undistorted record 14 is alongside
the secondary distorted record 55 with the cor
responding portions in opposite phase (that is,
one record passing the most light where the other
record passes the least light). By using the en 10
tire Width of the ?lm for these records, the ef
i'ect of ?lm noises (caused by the granular struc
ture of the photographic emulsion) is reduced.
This ?lm record is adaptable for use on re
producing apparatus of Fig. 6. With such an 15
arrangement the degree of reverse distortion is
adjustable, it being necessary only to change the
relative amount of light passing through the two
records to vary the degree of partial neutraliza
tion. This is due to the fact that the sound re 20
produced in speaker 8 is dependent only upon the
?uctuating component of the light striking the
photoelectric cell and not upon the total quan
tity, the non?uctuating component of light being
of zero frequency.
'
Fig. 3 shows a different type of record known
as the variable width type in which the amount
of iight transmitted through the ?lm is propor-.
tional to the width of the transparent portion ll
of the record. Otherwise it is the same as Fig. 2. 30
Fig. 4 shows a ?lm in which the direct and sec
ondary records Ill- and I5 of Fig. 2 have been
superimposed or combined into- a narrow record
18 at the side of the ?lm, leaving the rest of the
?lm to be used for motion picture reproduction. 35
With such an arrangement the degree of reverse
distortion is ?xed at the time the ?lm is made
and, therefore, must be accurately controlled in
the making.
,
Fig. 5 shows a ?lm in which the direct and 40.
secondary sound records of Fig. 3 have been com
bined into a single narrow sound record l9 at
the side of the ?lm leaving the rest of the ?lm
for the reproduction of motion pictures and is
similar in characteristics to that of Fig. 4.
45.
Fig. 6 shows the use of the sound record ?lm
t which is similar to the ?lm shown in Fig. 2 or
3 produced by the apparatus of Fig. l in a sound
reproducing apparatus having light apertures 20
and 2! for the direct and secondary sound record,
feed apparatus 22 for the ?lm, and a lens 23 for
bringing the light which passes through the
sound records into proper relation to a photo
electric cell controlling the ampli?er ‘! and
speaker 3. Light from sources 25 and 26 is di
rected against apertures 25! and 2i, respectively.
Thereby having a separate light source for the
direct and secondary records and thereby making
it possible to manually vary the degree of reverse
distortion continuously during the reproduction
of a record so as to obtain the best results at all
times.
Fig. '7 shows a method of reversely distorting a
radio broadcasting signal so as to effectively neu
tralize the distortion in all receiving sets using
a particular type of ampli?er, ampli?er 21 to be
as nearly perfect as possible and to correspond
to the direct circuit while ampli?er 28 to be the
same as that used in the said receiving sets, and
to correspond to the secondary or corrective cir~
cuit. The output from ampli?er 28 is made to
partially neutralize that of ampli?er 21 and
thereby obtain this reverse distorting e?ect elec
trically. Ampli?ers 2i and 28 may be of the
push pull type so as to eliminate harmonics, etc.
2,107,135
Figi 8 shows how ‘it would be possible to ac‘
complish this reverse distortion for neutralizing
the distorting characteristics of a loud speaker
‘ without ?rst permanently recording the sound.
verse distortion as practiced by this invention.
The values for this curve are arbitrary and have
conveniently been assumed to vary from 100%
perfect reproduction to 10% perfect reproduc
The fundamental difference between this circuit tion. ' t should be understood that any point
and the previous ones is in the way of avoiding
on this curve may represent a large number of
the time lag encountered by the air gap “A” diiferent frequencies that may happen to be re
between speaker B and microphone C‘. This is produced with the same degree of e?iciency.
accomplished by having two pick-up mi
The line P of Fig. 10 is assumed to represent
the desired energy level at which all frequencies 10
10 crophones D and Er located at different distances
from the source of vsound. Microphone D picks ' should be reproduced in order to give the proper
up the sound for the circuit having the arti?cial volume of undistorted sound under a given condi
distortion and which would correspond to the
circuit used forthe making of the secondary
The curve R of Fig. 10 represents the amount
record of Fig. l. Microphone E (which is lo
of distortion correction that may be effected by
cated at a greater distance from the sound source
the practice of this invention when using appa
than D) operates the circuit having no arti?cial ratus similar in its distorting characteristics to
distortion and which would correspond to that . the apparatus used to obtain curve Q.
part of Fig. 1 which records’ the direct record. 7
At the end of the Specification is a table show-7
By properly adjusting the distance of microphone ing how ‘the arbitrary values for curve R have
tion.
been obtained.
phone Dv it will readily be seen that the time lag
between speaker B and microphone C will be
balanced out. When the sound which is to be
Column 1 denotes the various frequencies which
are so distorted in the recording and reproduc
ing apparatus as to produce curve Q.
Column 2 gives the arbitrary values in percent
necessary that the mouth pieces of the micro
phones D and Ev be located side-by-side or even
converge into one in order to obtain the proper
time lag between the two microphones.
This is
In this table'— '
for the distortion arising within the recording
apparatus.
1.
Column 3 gives the relative percent of energy
recorded on the original or primary ?lm, and
accomplished diagrammatically in the ?gure in
which are the same as the values of column 2.
the form of a tube F which has the proper
Column 4 gives the arbitrary values in percent
for the distortion arising within the reproduc
acoustical properties and extends from micro
phone E to a point adjacent to the mouth piece
of microphone D.
CO Cl
.
E‘ from the sound source in relation to micro
. picked up comes from many different points it is
30'
.
30
. ing apparatus.
Column 5 gives the resultant relative reproduc
Fig. 9 shows a still different way of carrying V tion in percentage reproduced from the sound 35
out the objects of this invention and consists of
record of column 3 by the reproducing appara
two parallel circuits, energized by the same
tus column 4.
source, which may be similar to each other with
the exception that in one of the circuits a loud
40' speaker is inserted (having characteristics similar
to that of the speaker which is to do the ?nal
reproduction) in such a way as to dissipate the
electrical energy impressed upon it in the form
of sound energy. Now the frequencies at which
the speaker operates most e?iciently at will will
also be the ones that have the greatest amount
of energy dissipated. The result will be that the
distortion produced in this circuit by this energy
dissipation will be in the desirable direction.
‘ However, it will not be suiiicient to produce the
most advantageous results and, therefore, it will
be necessary to partially neutralize by the rela
tively undistorted energy of the other circuit in
order to increase this reverse distortion suf
?ciently.
Referring to Fig. 10, this is a diagram exhibit
ing the relative distortion correction that may’
be effected by the practice of my invention, as,
for example, when using apparatus similar to
60 that of Fig. 1.- The vertical lines denoted by
the letters “A to J”, represent various frequencies
handled by the apparatus and which correspond
to the sound frequencies which are to be re
produced.
The horizontal lines represent the
65 relative energy levels at which the said various
frequencies are reproduced, the scale of which is
logarithmically shown to the left as the “rela
tive energy levels shown in percent,” while to the
right are shown the corresponding values in TU
70 (transmission units, de?ned by the equation
TU=1O log. [P1132] when [P1P2l is the power
ratio.) The linear relation shown by curve Q
represents the relative reduction in volume of the
various important frequencies of a recording and
75 reproducing apparatus. when employing nov re~
V
.
The values in this column correspond to curve
Q of Fig 10.
Column 6 gives the relative percentage of the 40
reproduction of column 5 that is recorded on the
secondary record, when using recording appa
ratus having characteristics similar to that of
column 2.
7
Column 7 gives the relative percentage of the
recorded energy that is to be reproduced on ap~
paratus similar to that of Fig. 6, when the energy
recorded on the primary record of column 3 is
partially neutralized by subtracting 80% of the
secondary record of column 6.
'
.
Column 8 gives the relative percentage of re
production obtainable for the various frequencies,
when the partially neutralized record of column
'7 is reproduced on apparatus similar to that of
Fig. 6 and having characteristics similar to that 5.5
of column 4. These values correspond to curve
B of Fig. 10.
The comparison of curve Q and curve R of Fig.
10 shows quite clearly the result obtained by
subtracting 80% of the secondary record from 60
the direct record. This partial neutralization of
one record with another has the effect of re
ducing the volume of the reproduced sound as
well as tending to correct for distortion. There
fore, additional ampli?cation will be required in 65
the reproducing apparatus to overcome this re
duction in volume. Curve R2 shows the result
obtained by increasing the ampli?cation approx
imately four fold over that used in obtaining
curve R.
If the reduction in volume, caused by distor
tion of the various important frequencies were
such as could be represented by the letters A to
F, and there were no frequencies reproduced as
poorly as those represented by the letters G to
70
5.
2,107,135
J, it would be necessary to subtract only about
70% of the secondary record from the direct
record in order to obtain the most advantageous
results.
Column 9 and column 10 show the re
sults-obtained under this condition. Curve “S”
of Fig,'10 which corresponds to the values given
in column 10, shows clearly that the relative im
provement is greater in this case than that of
bining synchronously the products of two input
apparatuses in parallel with each other, one of
which input apparatuses is corrective and has
distorting characteristics over said band of fre
quencies similar to the distorting characteristics
of the reproducing apparatus, and applying said
combined products to said reproducing apparatus.
curve B and leads to the conclusion that the
10 less the distortion within the apparatus, still
greater will be the improvement effected by the
5. A method of obtaining faithful reproduc
tion of sound from sound-reproducing apparatus
including an ampli?er and a loud speaker, both 10
having distorting characteristics over a substan
tial band of frequencies, which method comprises
present invention.
Direct1 reciirtgi
neutra ize
y
.
so%
of SecOéld- m’éfg‘fve
ary recor ,
15
.
-
glglfgyggggé
Relative % oi
Fre-
by the direct
energy record- energy passed
qucncy
a
recording
circuit
ed on direct
record
Relative % oi
by the reproducing circuit
Sound
Relative "/aoi
Relative % of g?glggllgfvtggé
sound repro-
energy record-
mt is t'h‘gsame
duced
dueed for 500ondary record
ed on secondmy record
1 for both mi_
mmy and Sec_
from
neiiggrial
20
ondary circuits
when operating at fre
quency “A”
repro
20
direct
record
_,__.___
______ _,
Percent100
Percent l00
Percent 100
100
90
70
‘i0
75
100
60
80
100
90
70
90
75
100
60
8O
90
90
100
66
66
40
50
25
Percent
90
81
70
(‘:0
50
(i0
30
20
90
73
49
51
37
40
18
16
0
28
31
31
‘i7
116
(‘v8
46
67
100
100
l0
l0
10
92
I claim:
1. Sound recording means comprising a sound
recording circuit for making a permanent record
corresponding to the sound waves energizing said
circuit, a sound reproducing circuit energized by
the output of said recording circuit, and a sec
ond sound recording circuit having distorting
characteristics similar to the distorting charac
teristics of said first recording circuit energized
by sound reproduced by said reproducing circuit
for making a second permanent record on the
same recording medium as used for the record
ing from said first recording circuit.
Percent 100
30
09
having distorting characteristics over said band
of frequencies similar to those of the ampli?er
and loud speaker, respectively, of the reproduc
ing apparatus, and applying said combined prod—
nets to said sound-reproducing apparatus.
6. Apparatus for obtaining faithful reproduc
tion of sound from sound-reproducing apparatus
band of frequencies which method comprises
combining synchronously the products of two
sound input apparatuses in parallel with each
other, one of which input apparatuses is cor
rective and has distorting characteristics over
said band of frequencies similar to the distorting
characteristics of the reproducing apparatus, and
applying said combined products to said sound
reproducing apparatus.
3. A method of obtaining faithful reproduc—
tion of sound from sound-reproducing apparatus
including a loud speaker having distorting char
acteristics over a substantial band of frequencies,
which method comprises combining synchronous
ly the products of two sound input apparatuses
in parallel with each other, one of which sound
input apparatuses is corrective and includes a
loud speakers having distorting characteristics
over said band of frequencies similar to those of
the loud speaker used in the reproducing appa
ratus and applying said combined products to
said sound-reproducing apparatus.
4. A method of obtaining faithful reproduction
of sense~affecting waves from reproducing appa
ratus having distorting characteristics over a sub
stantial band of frequencies, which method com- -
prises applying said waves to said apparatus com
25
28
31
31
‘i1
27
23
17
other, one of which input apparatuses is correc CC Cr
tive and includes an amplifier and loud speaker
ing distorting characteristics over a substantial
70
Pcrcem‘2
combining synchronously the products of two
sound input apparatuses in parallel with each
2. A method of obtaining faithful reproduction
of sound from sound-reproducing apparatus hav
60
Percent
40
having distorting characteristics over a substan~
tial band of frequencies, which apparatus com
prises two sound input apparatuses in parallel
With each other, one of which input apparatuses
is corrective and has distorting characteristics
over said band of frequencies similar to the dis
torting characteristics of the reproducing ap
paratus, and means for combining synchronously
the products of said two sound input apparatuses.
7. Apparatus for obtaining faithful reproduc
tion of sound from sound-reproducing apparatus
including a loud speaker having distorting char
acteristics over a substantial band of frequencies,
which apparatus comprises two sound input ap
paratuses in parallel with each other, one of
which sound input apparatuses is corrective and
includes a loud speaker having distorting char—
acteristics over said band of frequencies similar
to those of the loud speaker used in the repro
ducing apparatus, and means for combining syn
chronously the products of said two sound input
apparatuses.
8. Apparatus for obtaining faithful reproduc
tion of sense-affecting waves from reproducing
apparatus having distorting char-acteristics over
a substantial band of frequencies, which appa
ratus comprises two input apparatuses in p.ar— 70
allel with each other, one of which input appa
ratuses is corrective and has distorting charac
teristics over said band of frequencies similar to
the distorting characteristics of the reproducing
apparatus, and means for combining synchro
6
s
‘
2,107,135
nously the‘products of said two input apparatuses.
9. Apparatus for obtaining faithful reproduc
tion of sound from sound-reproducing apparatus,
including an ampli?er and a loud speaker, both
having distorting characteristics over a substan~
tial band of frequencies, which apparatus com
prises two sound input apparatuses in parallel
with each other, one of which input apparatuses
is corrective and includes an ampli?er anda loud
speaker having distorting characteristics over said
band of frequencies similar to those of the am
pli?er and loud speak-er, respectively, of the re
producing apparatus, and means for combining 3
synchronously the products of said'two sound '
input apparatuses.
'
WESLEY WILSON.
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