US2150364A - Signaling system - Google Patents

Description

March 14, 1939." H 'w. DUDLEY SIGNALING SYSTEM Filed July 3l, 1937 3 Sheets-Sheet l ATTORNEY March 14, 1939. H. w. DUDLEY SIGNALING SYSTEM FiledJuly 5l, 1937 3 Sheets-Sheet 2 /NVEA/TOR H W UDL EV rates.

Patented Mar. 14, 1939 :lo o SYSTEM lHomer W. Dudley, Garden City, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., acorporation of New York Application July 31, 1937, Serial No. 156,707

This invention relates to signaling systems and has for an object the transformation of speech frequency signals into vibrations capable of being ability of the linger to respond to a frequency krrange that is designed for the ear with the same efficiency as it responds to the far lower frequency e range to which the ngeris accustomed. 20 In accordance with this invention it is proposed to transform a speech frequencyY message from aural material to tactile material capable of recognition and interpretation by the tactile sensitive regions so that We have what may be'termed a vbrotactile recognition of speech sounds.

`The information transmitted by speech does not absolutely require all the frequency space allotted to it in the human voice. can be worked out as to how wide a frequency 30 band is required asa minimum, for example, byl

40 the muscular, there is a very simple set of controlled motions of the muscular parts making up the speech signal. Several muscular elements move to form the speech signal but the rates of.

motion are the slow muscular or syllabic frequency As an example, the lips move for ordinary speech at a cyclic rate not ordinarily exceeding 'Z cycles per second for the fundamental or basic motion. Several other parts of the vocal systeml such as the lungs, uvula, tongue and teeth move 50 also, but they too move at slow rates'not ordinarily exceeding 'l complete cyclic changes per second.

However, there are two types of change, oscillatory in nature, that have motions occurring at 55 much higher lrates than .7 cycles per second but A specific case e claims.y (ci. 1re- 107) even these two types have a basic rate of change of not over 7 cycles per second. The first motionI is that ofthe vocal cords where the fundamental frequency for men is around 125 cycles per second, and for women over 200 cycles per second. 5 This motion differs from the others mentioned, in that itis a natural frequency of stretched cords. The tension of the cords is controlled volitionally and can only be changed at slow muscular or syllabic rates. The vocal cords not only have a high 10 fundamental frequency but they also give a wave shape which is rich in harmonics'up to several thousand cycles per second.V The lvocal cords have a steady energy source in the lung pressure which produces their vibration at their natural frequency depending upon the tension to which they are stretched, but this tension can change only at a slow rate, generally not exceeding 7 cycles per second.

.The second type 4of high frequency energy'g@ v source in speech production may for convenience be called a stricture. This stricture vor closing with air forced through to form a sort of hissing sound may occur betweenthe lower lip and up,- per teeth as for the f sound or between the tongue and front part of the hard palate' as for the s, or at other places for other unvoiced or breathed sounds. Such sounds have a continuous frequency spectrum with no definite fundamental frequency. It will be noted that in all-such unvoiced sounds the volitional control is again applied at the lower frequency muscular or syllabic rate generally not exceeding '7 cycles per second. v

From the foregoing ldetailed discussion of the 35 mechanics of speech sound productiomit is seen .that the various speech sounds are produced by voluntarily controlled variations in the muscular system at slow syllabic frequency rates of 7 cycles. per second or less. The important muscular ele- 40 ments or variables used in speech production are r.eight in number as follows: lung pressure; vocal cord tension and position; rear mouth resonance chamber; front mouth resonance chamber; opening from front to rear resonant chambers; open 45 ing from mouth; position of uvula; position of any stricture in the sound path.

Since the important muscular variables are only eight in number it is seen that the total frequency range required to produce sounds in the vocal system is very limited, it being limited in fact to the number of such variables multiplied by the frequency range required to express the motion of each, which may be 14 cycles per second if the reasonable assumption is made that the @5 fundamental rate of' change plus its first upper harmonic defines the motion reasonably well.

A simple ideal system for frequency range reduction in speech would be to analyze the speech sounds to determine what the important motions are and then prescribe a narrow frequency band, say, of 20 cycles width, to define each motion, but it is diiiicult if not impossible, to do it in this simple way because of the analyzing difficulties. Thus, for example it is very difficult 'to determine from a speech sound `iust what position the tip of the tongue had in its production. However, it is reasonably simple. to do this by the use of equivalent parameters. So long as the parameters are entirely independent we note mathematically that We can use any parameters We choose. Not only can they be chosen in any fashion provided they are independent, but if they are not entirely independent enough more parameters can be chosen to make up for the lack of independence. Thus, as a preferred example the sounds can beanalyzed into independent variables that are easily determined such as the power in each of several small Vfrequency sub-bands within the speech range. The power in each sub-band is notentirely independent of that in the other sub-bands but is sufficiently so that the average power level in, say, 8 or 10 sub-bands of the speech range will give us a very satisfactory set of parameters for speech definition. The analysis of the power level in small frequency sub-bands is preferably done electrically by circuit arrangements described'4 hereinafter.

In one specific aspect of the invention, thespeech message is analyzed electricallyfor its fundamental frequency and the average power in properly chosen sub-bands of frequency. In analyzing for the fundamental frequency a unidirectional current is produced whose magnitude defines the fundamental frequency and whose magnitude varies with the syllabic rate of change in the fundamental frequency. The magnitude of this unidirectional current will also be indicative ofthe presence of any unvoiced sounds which, having no definite fundamental frequency, will result in a substantially zero value of the delining unidirectional current. The analyzer may also -be arranged to produce separate unidirectional currents each defining the average power level in a chosen sub-band of the frequency range of the message. These unidirectional currents are preferably individually impressed upon vibrating devices for applying the vibrations to the human body at points where the sense of touch is Well developed. Thus, the vibrating devices may be adapted to contact with the fingers to convey sufficient information to the mind to enable the vibrations to be properly interpreted much in the same manner as if the sounds b efore analysis were received directly by the human ear, except that the speech defining signals by the above analyzing procedure have been reduced to a frequency range to which the sense of touch is readily capable of responding.

In a specific example the vibrating devices which designate the presence or absence of a fundamental frequency, and if present, the pitch of the fundamental frequency may be applied to the wrist, and each of. the ten ngers may rest on a vibrating device whose vibrations de'- f'lne the energy level variations in one of" ten sub-bands into which the speech frequency range has been divided by the analyzer.

However, if less completeinformation' is desired as to the message, as for example. where the invention is to be employed merely as an aid to lip reading, the number of independent variables chosen to define the speech message may be considerably reduced and for such uses it may be entirely satisfactory to divide the speech frequency range into, say, only four sub-bands of frequency and apply the fundamental frequency defining vibrations to the thumb of .one hand while the vibrating devices defining the energy level in each of the four sub-bands may be applied to the four fingers, thereby utilizing only one hand for securing the information to enable the speech to be interpreted. I

Referring to the drawings,

Fig. 1 is a schematic circuit embodying this invention by means of which speech or other vocal sounds may be transformed into defining signals capable of interpretation by the touch sensitive areas of the human body;

Fig. 2 is a view in perspective of one -type of receiving device for the speech analyzing circuit Fig. 3 is a top view of the device of Fig. 2;

Fig. 4 is a view partly in section of a nger actuating vibrator employed in the device of Fig. 2;

Fig. 5 is a view partly in section of the pitch controlled vibrating device of Fig. 2;

Fig. 6 is an alternative form of the vibrating device of Figs. 4; and

Fig. 7 is an alternative form of the vibrating device of Fig. 5.

Fig. 1 illustrates a preferred arrangement of this invention by means of which speech or other vocal sounds may be analyzed and transformed into speech defining signals of low frequency capable of be'ing correctly interpreted by the touch sensitive areas of the human body.

Speech may be regarded as having a dual'characteristic. On the one hand we have xed parts or elements setting,up oscillatory waves containing high frequency patterns. On the other hand `we have varying parts or elements setting up modulatory WavesI of low syllabic frequency pattern. The fixed features include: (a) existence of definite frequency sub-bands in which the 'power distribution is sensibly uniform; (b) the existence of a frequency spectrum that alternates from a continuous type of spectrum with no deflnite fundamental frequency to a discrete type with varying fundamental and with all principal harmonics always present; and (c) the fact that time variations of the fundamental frequency and of the power in the frequency sub-bands occur only at syllabic frequency rates. The variable features include: (a) the magnitude of the average power in each sub-band: and (b) the nature of the signal spectrum as to whether it is continuous or discrete, and in the latter case, the frequency of the fundamental frequency and its possible Variations from sound to sound.

Since there is foreknowledge as tothe fixed features or characteristics of the speech signal it is unnecessaryto transmit information `regarding them, to the touch sensitive areas of the human body. It is sufficient merely to transmit information defining the variable characteristics of the signal.

The first-mentioned variable feature is the magnitude of the average power in each sub-band into which the speech signal is divided. The number of sub-bands chosen depends upon the degree of intelligibility desired, the greater the width depending upon its importance function in the production of speech as described. for example, in my copending application Serial No. 47,393,

led October 30, 1935, on Signal transmission.

"I'he second-,mentioned variable feature of speech concerning which information should be transmitted is the nature of the speech spectrumas to whether it is continuous without any definite fundamental frequency or whether it is a discrete spectrum, and in the latter case as to what 4is the frequency of the fundamental frequency for each voiced sound analyzed. This information is transmitted in a simple manner by the apparatus of Fig. 1.

In the arrangement of Fig. 1 the speech or other vocal sound to be analyzed is picked up by a suitable microphone 20 and amplified to a desired level by an amplifier 2i whose output is dlveded intd a'frequency pattern control circuit I FP and an amplitude pattern control circuit AP.

of speech if the fundamental 1sI low. This is done in case the'fundamental frequency may be The frequency pattern control circuit FP takes advantage of the fact that in vowels and other sounds having a decided fundamental frequency in the' range from 80 to, 320 cycles there is a high transmitted through circuit FP is not sucient to energize the vibrating device 22.

Referring more particularly to the details of the circuit FP a band-pass filter Fo selects the band from 50 to 500 cycles of the voicezsignal so as to be sure to include at least two harmonics 8d cycles or so, and, therefore, insufficiently amplified by amplifier 2 I. The output of this bandpass filter Fo is fed to detector D which may be merely some small copper oxide elements. This insures that a fair amount of the fundamental l frequency will be present if the power level is sufficiently high as in the case lof vowels. The output from detector D is sent through an attenuating network E1 more frequently termed an equalizer, which has a loss increasing with frequency for the purpose of insuring that the fundamental frequency comes out at a higher level than any particular harmonics that may bplgggesent. For practical purposes this puriiies the fundamental tone. Next, the output from this equalizer Ei is fed to a constant output amplifier LA 'so that from this amplifier 'there is obtained es` sentia-ily a single frequency, the fundamental frequency of the speed signal'at a constant powerlevel regardless .of what the 'frequency is.

This fundamental frequency may be from about cycles tol-329 cycles.' Next, we' pass this powerthrough an equalizer Ea similar to the one del scribed previously, except that the output from this equalizer increases as the frequency irlcreases. This output is sent through another copper oxide detectorDo which gives essentially a direct current bias which uctuates as the fundamental frequency of speech ductuates, that is, at syllabic frequencies. The detector output is then sent through a low pass fllterFso cutting on at 20 cycles so that the unwanted higher frequency components are eliminated. This output is'now used as a biasing current applied to the winding of the velectromagnetic device 22 whereby v the armature of device 22 is retracted an amount which is proportional to the amplitude of the deiining current from filter F30. That is, the tension exerted on the armature of device 22 will be proportional to -the frequency of the fundamental frequency so that a touch sensitive area of the human body subjected to the strength of the armature pull will be subjected to a pressure which defines the fundamental frequency of the energized sound. For a' voice with a high pitch the pressure on the skin will be high'while for a voice with a low pitch the pressure will be low, and the pressure will vary with any syllabic variations in the pitch of the voice. `This will lead to a natural interpretation of the pitch by theperson subjected to the tension from device 22 since in producing speech sounds the pitch ofthe voice increases with increased tension on the vocal -cords.

However, when the frequency pattern control circuit FP receives a speech signal having a continuous spectrumsuchas when a sibilant consonant sound is impressed on microphone 20, the entire frequency spectrum is at a low level with no single frequency emphasized over the others.

Hence, for such sounds there will be substantially no energy output from low pass lter F30 and hence device 22 will not be energized. The absence of tension on the touch sensitive area subljected to device 22, therefore, indicates an unvoiced sound.

One form the frequency pattern defining element 22 may take is illustrated in detail in Fig. 5'

Where it is shown as an electromagnetic device of the dynamometer type vwhere an increase in current causes an increase in pull on a mechanical part. moving coil 2t suspended in the slot. The two conductors 25, 26 are so connected with'respect to the polarity of the current output of filter F3 that the impressed current creates a downward 'pull on coil 261. Mounted as a part of the casing tened'to coil it, extend upwardly through aper 'tures in block 28 and terminate in eyes joined by a light-weight chain 4l.

The length of chain t1 should be such that when the users wrist lies in the hollow of block 2B the Wrist in the absence of any applied current from channel FP lwillsupvport-coil 2d approximately in the position shown in Fig. 5. The greater the current applied to coil 2li the greater will be the downward pull on the coil, and hence the tension exerted by chain M It comprises a slotted magnet 23 with a on the wrist of the user will be proportional to the frequency of the fundamental frequency of the voiced sounds, while an unvoiced sound having no fundamental 'frequency will supply subterpret the pitch of each analyzed sound as well vim as enabling one to distinguish between voiced and unvolced sounds.

There remains to be described the apparatus for analyzingthe speakers energy in the different frequency vsub-bands of the speech frequency range in order to determine the amplitude pattern characteristic of each speech signal. YThe amplitude pattern control circuit AP of Fig. 1 is essentially a circuit for measuring how much power there is in the speech signal in chosen small frequency bands and for transmitting this information by control currents to a plurality of vibrating devices, one for each sub-band. The amplitude pattern circuit AP'at the output of amplifier 2| is divided by suitabley band-pass filters F1 to F1o cycles; channel APs passes the frequency range 1500-1950 cycles; channel AP6 passes the frequency range 41950-2350 cycles; channel AP7 25.

passes the frequency range 2350-2900 cycles; channel APs passes the frequency range 2900-3750 cycles; channel APQ passes the frequency range 3750-4950 cycles; and channel APw passes the frequency range 4950-7100 cycles.

Considering the channel AP1, for example, the output from the 250-530 cycle band-pass llter F1 is fed to detector D1 which, for instance, may be of the copper oxide type. The syllabic fre- Iquenciesl in the output from the detector D1 are passed through a 20 cycle low pass filter F31 and used to energize a vibrating device 50 so that the magnitude of the vibrations of the armature of device 50 defines the average amount of power of each speech signal in the frequency band from Z50-530 cycles, and the magnitude of the armature vibrations will increase or diminish at ,a syllabic rate in response to the syllabic variations of the power level in the designated sub-band.

Electromagnetic device 50 may be of various types, one of which is shown in greater detail in Fig. 4. The solenoidal winding 60 which is connected with the output of filter F31 has a magnetic core plunger 6| slidably mounted in a stationary collar 62 having a vertical slot 63 in which slides a pin 64 fastened to plunger 6| so as tolimit the motion of the plunger. A coiled spring 65 serves to bias the plunger 6| to anoutward position while the plunger will be pulled downwardly an amount proportional to the amplitude of the current through'winding 60. The upper end of arm 6| has a key or finger rest 10 so that the syllabic vibrations of armature 6| will be received by the finger resting on key 'l0 to enable the user of the device to receive accurate information as to the amount of power in the sub-band 250-530 cycles and the syllabic variations of the this sub-band.

Channels APz to APm are similar to channel AP1 just described exceptA for the' frequency range analyzed by each channel and vibrating devices 5| to 59 are similar to device 50 just described.

Filters F1 toFw are alike except as to ltheir bandpass range as indicated in the figure; detectors D to D10 are alike; and filters Fao to F40 are alike in that each suppresses all frequencies above 20 cycles.

In order to receive tactile information suflicient i.

power level inupon the ten finger rests to 19 and may surround one wrist. with the chain 41 of vibrating device 22. The tension exerted on the wrist sur- Y rounded by chain 41 will give intelligible informationas to whether each element of the signal is voiced or unvoiced, and if voiced, information as to the frequency of the fundamental frequency of the signal. The magnitude of the vibrations of finger rests 10 to 19 will convey to the person the amplitude pattern .of each signal component in such a form that each component may be correctly interpreted.

One type of assembly for the pitch defining means 22 and the amplitude pattern defining means 50 to 59 is disclosed in Figs. 2 and 3. Referring to these fingers, there is shown a housing 90 adapted to enclose relays 22 and 50 to 59,

inclusive, the electrical connections for which are supplied by a suitable cable 9|. The upper surface of the housing has ten apertures 92 to 10|, inclusive, through which project the nger rests 10 to 19, inclusive, in the order named, that is, finger rest 10 projects through aperture 92, and finger rest 19 projects through aperture 10|. 'I'his means, as shown in Fig. 2, that the little finger of the left hand will receive defining signals for the lower sub-band and the little finger of the right hand will receive defining signals for the highest sub-band, with the intermediate fingers receiving information as to the power level of the intermediate sub-bands. The apertures 92 to 10| are so arranged that the ten fingers may comfortably rest on the'vibrating keys 10 to 19 with the hands in a natural position without strain or stretching. The housing 90 also has an extension rest |02 for the right-hand wrist and an extension 28 for the left-hand wrist. Exten- Asion 28 which has previously been described in left wrist and'by the ten fingers with the apparatus of Fig. 2 suitably connected to the analyzing circuit of Fig. 1 will enable the user of lthe apparatus to understand and properly interpret the speech or other signals picked up by microphone v20.

t is, of course, to be understood that microphone 20 may, if desired, be located at a remote point from the rest of the apparatus but connected thereto by suitable means such as a telephone line. Since the frequency pattern control branch FP tends to have more inherent delay than the amplitude control branch AP it will-generally be desirable to have a certain amount of delay in common with all the amplitude control circuits AP1 to AP10 and such a delay equalizer DE is shown in Fig. 1 at theV output of amplifier 2|.

An alternative type of vibrating device for us in each amplitude'pattern channel is shown in Fig. 6. The solenoidal winding |05 is adapted to be connected to the output of one of the channels AP1 to AP1o and has a magnetic core plunger' |05 adapted to be actuated by the amplitude deiining variations of the current supplied to windling |05. For `zero currentthr'ough winding ,|05 the lower end of plunger |06 is adapted to rest 75 `against a suitable stop-|01. Pivomuy munted on plunger |06 is a key plate |08 hinged at one end to a support |09. The free end IIO of key |08 is connected to serve as a restI for a finger in order that the defining vibrations of key |08 may be conveyed to the finger resting thereon. The'mechanical vibrations received by the nger from the device of Fig. 6 will be greater in amplitude when the device of Fig. 4 is employed.

Fig. 7 represents an alternative type of vibrating device which may be employed in place of the device of Fig. 5 for the purpose of receiving the frequency pattern defining currents from channel FP of Fig. l.` The s'olenoidal Winding III may vbe connectedto the output of filter Fao to receive the defining currents from that filter. 'I'he plunger type magnetic core II2 vibrated by 'the current variations through `windi ng III has pivotally connected thereto one end of aleverA I I3 which is pivoted near its other end on a stationary support II4. The end II5 of lever II3 is shaped to form a finger rest. After a finger is placed onfinger rest II5 a slidable extension I I6 should be lowered to firmly contact with the upper surface of the finger for thennormal position of lever I I3 in the absence of any energizing current through Winding III. The upper finger contacting member IIE may be clamped in the desired position by set screw.I.I1. Spiral spring II8 in an obvious manner normally maintains plunger II2 biased to an outward position and -force of spring IIB.

the electromagnetic action of-winding III will serve to pull plunger II2 downwardly against the It will be apparent from the foregoing description that the users finger placed in between-,members II5 and IIB will be subjected to a varying pressure by .the action of the currents defining the frequency pattern from channel FP in order that the user of -the device may properly, interpret the pitch ofthe speech signals and determine whether each speech component is a voiced or unvoiced sound. The de' vice of Fig. 7 is particularly intended for use where there are less 'than ten amplitude pattern channels so thatone' finger may be utilized for receiving the frequency pattern defining signals vwith any desired. number of the other fingersutilized to receive the amplitude vpattern defining -will be satisfactory v-to employ fewer amplitudewhile the other 'a person with normrl hearing.

As previously stated, it may be desirable for high quality interpretation of the speech to em ploy as high as ten amplitude pattern channels as shown in Fig. 1. But for many purposes it pattern channels, particularlywhen the apparatus of the invention is to be usedas an adjunct to lip reading. For example, one vibrating device for pitch definition and fourvibrating devices for defining, certain frequency sub-bands of speech will give far better speech recognition than is obtainable bylip reading alone. Thus, ifV one vibrating device is employed for speech definition and four vibrating devices for amplitude pattern definition, then only the fingers of one hand will be needed to contact withthe vibratingv devices hand will be free fd!I other uses. It is also within the scope of the invention` to apply the pitch and amplitude defining vibrating devices against adjacent parts of the forearm or other parts vof the body, 4thereby freeing both hands for other 'usesin the same manner as for If fewerthan-ten channels are. employed for amplitude definition-it will, of course,'be necessary to alter the frequency sub-bands assigned to each channel over those given for illustrative purposes in Fig. l for lters F1` to F1o. For example, with only four amplitude pattern channels the lowest channel may pass the frequency range 100 to 500 cycles; the second channel may pass the frequency range 800 to 1300 cycles; the

third channel may pass the frequency range 2300 to 3000 cycles; and the fourth channel may vpass the .frequency range 3600 to 5000 cycles.

However, in most instances it is not essential to adhere to these values as other widely differing values may be employed with satisfactory results.

-In the circuit diagram of Fig. l certain filters Fao to F40 are'disclos'ed for the purpose of eliminating all frequenciesabove 20 cycles. It will frequently be found' unnecessary to employ these filters in view of the fact -that the fiesh itself will damp out the higher frequencies at a sufiiciently rapid rate.

The above described embodiment of the invention is representative of other embodiments this invention may possess commensurate with said low frequency waves having a fundamental Ifrequency of less than 10 cycles per second, a

plurality of independent vibratory members adapted to be applied to the touch sensitive areas of the human body, and means for controlling each of said vibratory members in accordance with one `of said defining waves.

2. In a si aling system, means to produce a signal conta ning variable information and invariable information represented by a complex electrical wave of a Wide frequency bandv ofy vspeech frequencies, means to analyze said wave and derive therefrom a simple set'of parameters having approximately the number of 'degrees of freedom yof the variable elements of the signal source, means to translate said set of param eters into a set of low frequency defining Waves that respectively define the variations of said parameters, each'of said low frequency waves having a fundamental frequency lof less than I0 cycles per second, a plurality of electromagnetic devices each having a winding and an armature.-

said armatures ,being adapted to be applied to the touch sensitive areas of the human body, and.

meansv for transmitting each of said defining -waves to one of said windings to the exclusion of waves representing said invariable information.

3. A system for translating a message of a range of frequencies adapted to be interpreted by the human ear into a range of frequencies capable of interpretation' by the Atactile sensitive areas 'of the human body, comprising means to analyze said message and derive therefrom a set of substantially independent parameters correspondingin numbertp a selected number of the important independent movableelements ofthe vocal system involved in speech production, means to translate saidsetof parameters into a. set. of low frequency dening waves, each having 'a fundamental frequency of less than 10 cycles per second and each having an amplitude representing an essential characteristic of the message, individual finger supports, and means for vibrating each of said supports in accordance with one of said defining waves.

4. A system for translating a speech signal of a range of frequencies adapted to be interpreted by the ear into a range of frequencies capable of interpretation by the touch sensitive areas of the human body, inl which the generation of said signal involves independently controlled sluggish muscular movements .as well as the rapid vibra tion ofthe vocal cords, said system comprising means for transforming said signal into a plurality of substantially independent low frequency 'waves each of a fundamental frequency less than ten cycles per second, said'waves collecti'vely defining said sluggish muscular movements, and vfinger' supports Vindividually vibrated by said low frequency Waves.

5. A system for communicating a message represented by a complex electrical Wave of a Wide frequency band. within the speech frequency range, said system comprisinga plurality of vibratory members adapted to contact With the touch sensitive areas of the human body, means for dividing said band into a plurality of subbands, separate means for demodulating each sub-band, and means for controlling each of said members in accordance with one of the demodulated currents.

6. A system for communicating a messagev represented by a complex electrical Wave of a Wide frequency band Within al speech frequency range, said system comprising a plurality of vibratory members adapted to contact with the touch sensitive areas of the human body, means for selecting a number of substantially inde.- pendent characteristics of said wave, means for producing a plurality of low frequency currents each having a fundamental frequency of less than 10 cycles per second and each defining one of the characteristics of said wave, and means for controlling each of said members in accordance with one of said defining currents. p

7. A system for communicating a message represented by a wide frequency band within the speech frequency range comprising a plurality of vibratorymembers adapted to contact with the touch sensitive areas of the human body, means for dividing said band into a plurality of subbands,.separate means for deriving from each sub-band a low frequency wave of a fundamental frequency of less than ten cycles lper second, which wave defines the average energy levelin the sub-band, and means for controllingk each of said members in accordance with one of said dening waves. p

8. A system for translating a speechsignal of a range of frequencies adapted to be interpreted by the ear into a low frequency range capable of interpretation by the touch sensitive areas of the human body in which the generation rof said signal involves independently controlled sluggish muscular movements as well as the rapid vibration of the vocal cords, said system comprising means for transforming said signal into a plurality of substantially independent syllabic frequency Waves each of a fundamental frequency of less than l10 cycles per second, said Waves collectively defining said sluggish muscu- -larmovements analyzing means for producing from said signal a low frequency Wave of a fundamental frequency of less than 10 cycles per second whose amplitude defines the rate of vibration of the vocal cords, a pluralityof vibratory members adapted to contact with the touch sensitive areas of the human body, means for controlling each of a plurality of said members in accordance with one of said syllabic frequency waves, and means for controlling another of said members in accordance with said low frequency Wave which denes the rate of vibration of the vocal cords.

9. A system for communicating a message represented by a Wide frequency band Within the speech frequency range comprising a plurality of vibratory members adapted to contact withl the touch sensitive areas of the human body, means for dividing said band into a pluralityy of subbands, means for deriving from each sub-band a low frequency Wave of a fundamental frequency Y of less than 10 cycles per second and. Whose amper second whose amplitude defines variations in the frequency of the fundamental frequency of said message, and. means for controlling another of said vibratory members in accordance with said wave which defines the fundamental frequency of the message.

HOMER W. DUDLEY.

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