US3852535A - Pitch detection processor - Google Patents

Pitch detection processor Download PDF

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Publication number
US3852535A
US3852535A US00416623A US41662373A US3852535A US 3852535 A US3852535 A US 3852535A US 00416623 A US00416623 A US 00416623A US 41662373 A US41662373 A US 41662373A US 3852535 A US3852535 A US 3852535A
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pitch
signal
pulses
marker
period
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J Zurcher
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ZURCHER JEAN FREDERIC
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ZURCHER JEAN FREDERIC
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
    • G10L25/90—Pitch determination of speech signals

Definitions

  • the pitch of speech waves is usually referred to as the repetition of wave patterns which are formed by certain combinations of frequency components having definite amplitude levels and frequency ratios, one with respect to another.
  • the parameters which are extracted from the speech wave are the energies contained in adjacent frequency bands of the speech wave spectrum, a voiced-invoiced sound decision and pitch.
  • the voiced-invoiced sound decision and the pitch are used to specify the harmonic content of the complex speech wave.
  • pitch detectors are described in the prior art. They generally detect the fact frequency of a complex speech wave by selecting the major peaks of said wave by means of an arrangement comprising RC elements to which is applied the rectified complex wave voltage. The purpose of such an arrangement is to charge the capacitor of the RC circuit to the level of a major peak and eliminate the minor peaks by way of a slow discharge through the resistor of the circuit.
  • the pitch detector 'converts the analog speech signal into a signal which retains the rising front edge of the major peaks, replaces the descending rear edge of these peaks by a decaying waveform and produces marker pulses each time the amplitude of the speech signal exceeds the decaying waveform signal.
  • Line 1 of FIG. 9 shows nine idealized pitch periods 90 and 92-99, whereof the seven latter ones comprise two marker pulses, 930, 931, 940, 941, 950, 951, 960, 961', 970, 971, 980, 981, 990, 991, the first period 90 being equal to two times the others.
  • the periods 93-99 is retained since they 'are each formed of two periods largely differing therebetween and they would be replaced by the repetition of seven times the period 92.
  • marker pulses 931, 941,... 99lared since they are very proximate to pulses 930, 940,... 990 respectively and periods 93-99 are detected without error (line 20f FIG. 9).
  • FIG. 1 shows a diagram in the form of blocks of the pitch detection processor according to the invention
  • I showsadetailed diagram in the form of blocks of the major peak selector unit 3 of FIG. 1 according to the invention
  • i shows adetailed diagram in the form of blocks of the major peak selector unit 3 of FIG. 1 according to the invention
  • FIG. 3 shows one embodimentvof one of the two integ'ratorsofFIG.2;"'
  • FIG. 3a shows a diagram of signals illustrating the operation of the apparatus of FIG. 2;
  • FIG. 4 shows a detailed embodiment in the form of blocks of the processor unit 4 of FIG. 1 according to the invention.
  • FIG. 5 shows a second diagram of signals illustrating the operation of a duration modulator comprised in the processor unit of FIG. 4;
  • FIG. 6 shows the program of the pitch detection processor
  • FIG. 7 shows a third diagram of signals illustrating the operation of the processor unit of FIG. 4;
  • FIG. 8 shows the mesuring and storing circuit of the pitch detection processor
  • FIG. 9 is a diagram of signals already explained in the introductory part of the specification.
  • FIG. I shows the general arrangement of the apparatus according to the invention in the form of blocks.
  • This FIG. 1 shows the input circuit 1 which generates the vocal signals to be analysed in relation to the voiced-invoiced sound decision circuit 2 and the major peak selector unit 3.
  • the two blocks 2 and 3 are connected to oneanother and with the processor unit 4, itself in communication with the measuring and storing circuit 5 controlled also by the decision circuit 2.
  • the circuit 2 which determines the presence or absence of voicingin the signal to be analysed and generates a corresponding decision signal P or F is of a known type. It applies the principle according to which the energy of the voicedsounds beingiespecially concentrated in the band of frequencies lower than 700 Hz 'whilst that of the non-voiced sounds is beyond 1,500 Hz thus it suffices to compare the energy E, of the signal to be analysed taking in the band beyond 1,500 Hz with the energy E, of the signal taken below 700 Hz.
  • a circuit detecting the presence of speech isaddedQThis circuitcomprises a'chain similar to the two preceding ones but where the frequency pass-band isthe ordinary vocal band without limitation.
  • a comparator changes state when a threshold fixed experimentally is passed. Insofar as this threshold is notpassed the apparatus considers that the signal submitinputs of two chains of circuitsthe different elements als with a subscript] for the upper chain and a subscript 1 for the lower chain.
  • These two chains comprise amplifiers 20, and 20 the bottom chain being provided in addition with an analog inverter 19,.
  • the signal a coming from 1 therefore is subjected to the same treatment in these two chains except inversion, the top chain being allocated to the treatment of positive major peaks and that of the bottom to the treatment of negative major peaks. It suffices therefore to describe the top chain.
  • the amplifier 20, is followed by an expander 21, comprising a diode in parallel with a series resistor connected to a shunt resistance.
  • This expander of known type (see US. Pat. No. 2,957,134 issued Oct. 18, 1960 to M.V. KALFAIAN) has function of favouring the passage of the positive peaks for which the diode presents in fact a low resistance whilst the remainder of the signal'which passes this diode is weakened. This expander therefore renders the peaks finer so as to define better their position in time.
  • the signal thus treated is admitted into an impedance matching CCT 22, which does not transmit its direct component and does generates a signal u,.
  • Impedance matching CCT 22 allows matching the output impedance of the expanser 21, to the input impedance of the comparator 28, as regards the signal u, and to the input impedance of a second v ing from the comparison is applied to adapter 26,
  • the output signal of adapter 24, is applied to the input-of amplifier 20, where it is added to the speech signal.
  • this output signal is applied to monostable flipfiop 27 which is triggered by the rear front of the comparison-impulse (FIG.'3a, line g) and controls bistable flipflop 29 (FIG. 3a, line h).
  • the signal P coming from the voiced-unvoiced sound decision circuit 2 controls the switch 17.
  • FIG. 3 The diagram of one of the two integrators 25, and 25 is given in FIG. 3. It comprises two transistors mounted in the so-called Complementary two-stage emitter follower, PNP 31 and NP N 30, the output terminal of which can be .groundedeither through'a RC network 32, 33 or through this network in parallel with an additional resistor '34; this resistor is inserted by switch 17.
  • the switch 17 behaves like a variable resistor passing progressively from a zero value to an infinite value within four to five periods when the signal P passes from state 0 to state 1".
  • the integrator has therefore two time constants RC and R R, C/R R, (R, R, resistances of resistors 32, 34; C capacitance of capacitor 33).
  • the two transistors begin to block.
  • the voltage u then becomes greater than the voltage u, the comparator 28, changes state which has the effect of activating switch 17, and shortcircuiting the input of the integrator 25,.
  • the two transistors 30 and 31 then block completely and capacitor 33 discharges into the equivalent resistance R R,/R R,.
  • capacitor 33 is effected through an equivalent resistor which has two resistance limits namely the resistance of resistors 32 and 34 in parallel and the resistance of resistor 32 and progressively varies between these limits due to the passage of the transistor constituting the switch 17 from the conductor state to the blocked state.
  • FIG. 3a shows signal waveforms intended to explain how the circuits of FIG. 2 operate.
  • Line a shows the speech signal after low-pass filtering.
  • the direct component CC of the speech signal is replaced by a larger direct component CC which results in the cancellation of the minor peaks.
  • the signal 14 is replaced by a decaying signal u, in the intervals between the major peaks.
  • Line d shows the marker pulses derived from the major peaks.
  • the decaying part of the signal hasa too weak slope to intersect the major peak at T,.
  • this major peak would not give rise to any marker pulse if special precautions were not taken.
  • a part of signal u is subtracted from signal u, by means of capacitor 28,, and resistors 28, and 28,;,.
  • the decaying signal instead of being a mere decreasing exponential signal, is a signal fluctuating about this exponential signal which, this time, intersects the major peak at T, (FIG. 3a, line j).
  • the lines 1 and 3 illustrate the usual operation of the apparatus and the corresponding marker pulses.
  • the instant of occurrence of the forward front of the marker pulses is determined by the intersection of the curves representing u, and u, and this intersection is subject to displacements in time imparted by the variations of amplitude of the voltage 11,. This is shown by the peak in bloken line of line f and the corresponding marker pulse in broken line of line g.
  • the signal j generated by flipflop 29 and the signal P generated by decision circuit 2 controls the processor unit 4 of FIG. 1 the detailed diagram of which is given in FIG. 4.
  • the output signals of the processor unit 4 are the signals F, and F 1
  • the signal P is utilised directly to reset a counter formed by the flipflops 471,- 472 and 474 and the complementary signal I obtained in. the inverter 452 is utilised to feed the OR-gates 44 45 44, and 45,.
  • These gates serve similar members saw-tooth voltage generators 40,, and 40, and switches 43,, and 43,, said switches being identical with switch 17 of FIG. 2 and'controlling respectively .pulse duration .modulators 41,, and 41,-.
  • the saw-tooth voltage, generators are started and stopped by the fronts of pulses P and by control pulses Q or Q, derived from the negative fronts of pulses j.
  • the saw-tooth voltage 502 decreases from zero to a level 503 reached at the next control pulse.
  • the duration modulator has stored therein the level 501 which was the maximal amplitude reached by the saw-tooth voltage 500.
  • the saw-tooth voltage 504 and an attenuated level 503 derived from level 503 through an attenuator connected between duration modulators 41,, and comparator 42, are applied to the said comparator.
  • Comparator 1 42 produces pulses e whose front edges coincide with the equality of the dietary saw-tooth voltage and the attenuated maximal level of the preceding saw-tooth voltage and whose rear edges coincide with the control pulses.
  • the output signals of the comparators 42,, and 42 are put in form and amplified in amplifiers 48 48, and 48, which have two outputs and giving complementary signals.
  • marker pulses when the actual pitch period is longer I than the preceding period by a given amount.
  • the amount is defined by the attenuator connected to the input of the comparator across the lead coming from the duration modulator.
  • signal j coming from the selector unit 3 is applied to the input of the monostable flipflop 453 which utilises the descending fronts of this signal and generates pulses Q and 6 (FIG. 7) having a duration of 10 ms.
  • the signal Q drives in its turn a monostable flipflop 454 which utilises the ascending fronts of the driving pulses and generates pulses of duration equal to ms and designated by Q, and 6 (FIG. 7).
  • the signal 6 controls AND-gates 456 and 462 and together with signal P OR- gate 45,.
  • This signal I is also applied to the input of the -OR-gate 44,, together with signal Q, and s ignal (2 causes the flipflops 471 and 472 to progress..Q, also resets the flipflop 445 which counts pulses-".
  • The, flipflops 471 and 472 control the AND-gate 473 which when these flipflops are both in state one and when P is also instate l is open and sets flipflop 474 in state O.
  • the signal? is in the state 0, it resets the flipfiops 471, 472 and 474.
  • the flipfl'op 455 produces from pulses 'the pulses 0,
  • this same signal F is inverted in 463 and becomes F, whichis applied to the measuring and storing circuit 5.
  • Thesignal F is also applied to OR -gate 464 together with the product (e, X e,') to give the signal v which controls the fl'ipflop 466 which supplied the signals B, and I31.
  • the circuit of FIG. 4 operates according to the algorithm of FIG. 6. 1
  • the j pulses are counted, the first being that which appears after the signal P has taken the value 1 and has reset the counter formed by flipflops 471,472, 474. If three j pulses have been counted, 471 and 472 are both in state one and flipflop 474 changes over to state one,
  • Pulses j control the circuit chain producing pulses e for detecting whether a period T, is shorter than the preceding T--, or not:
  • the signal 6 changes over flipflop 455 to 0, which activates OR-gate 461 and AND-gate 462.
  • the signal F is then applied to measuring and storing circuit 5.
  • pulse F is generated or not according to the value of signal B which answer the question: Was pulse (j 1) taken into account or not? If the impulse (j 1) has not been taken into account, F l, the OR-gate 461 is active and F, is generated and causes the measurement of T, by the circuit On the other hand it must be verified that the period T, determined by the interval between two impulses of F is comprisedbetween the limits given by the previous situation namely the period T with a tolerance fixed by a parameter 6 as previously which-poses the question: i
  • FIG. 7 shows a complete operation of a system from the signal a similar to the signal a of FIG. 3a.
  • the signals'h and i are generated as has been stated and are shown here by their complements F and from where the output signal j of the flipflop 29 (FIG. 3) results.
  • These pulses j give'rise to pulses Q in 459 and pulses Q, in 454 (.FIG. 4).
  • the signal P obtained in the decision circuit 2 triggers the saw-tooth voltage generator 40,, (FIG. 4) and the duration modulator 41
  • the comparator 42 gives rise to the signal e at the output of amplifier 48
  • the negative front of this e signal causes the flipflop 455 to change over and this flipflop is reset by the 6 signal which gives. the signal 5,.
  • the first Q, pulses located at the left hand side of the vertical line xx correspond to the start of a voiced sound and it requires atleast three Q, pulses for the counters 471, 472 causing the change-of the state of 474 generate the signal 0.
  • Fiipflop 474 is reset when the signal P comes to zero.
  • the AND-gate 456 the product (0, X6) is obtained and causes thestate of 458 to change.
  • the OR-gate 461 generates the (6+ b) signal.
  • This signal is applied together with signal 6 to AND-gate 462 which generates signal F the negative fronts of which give rise to the signal O by the action of monostable flipflop 459.
  • the vertical xx determines a transitory time in the course of which the apparatus detects the nature of the signal a, voiced or unvoiced, and defines the period.
  • the continuation of the diagram of FIG. 7 concerns the second stage of the processor unit of FIG. 4 in which are located the sawtooth voltage generator 40 the duration modulator 41, and the comparators 42 and 42 These comparators produce the pulses e and e which together with the signal F are applied to OR- gate 464 to form the signal v.
  • the flipflop 466 changes state on the ascending fronts of v and generates the-signal fi which together with (e X e',) and 0 is applied to OR-gate 468 for generating the train of pulses F authorizing or not the transfer of T; in the register of the I measuring and storing circuit 5.
  • a signal Q is produced by the monostable flipflop E7 activated by the rear edges of the signal (F, X F generated by the AND-gate 470.
  • the measuring and storing circuit 5 whose input signals are the signals F, F, and F
  • the signal P when it is in the state 1 resets flipflop 701 and this flipflop is set to one by the signal F delayed by the delay circuit 703; the signal (P X F generated by AND-gate 702 serves as a reset signal for the counter 704 which comprises here seven flipflops and which counts the clock pulses generated by pulse generator 700.
  • the signal (F X E) is effected by means of inverte 705 and AND-gate 706. This signal is utilised as a transfer signal for transferring the contents of counter 704 into register 707.
  • the contents of this register is received in decoder 710 and when it is greater than a predetermined number, a displacement order of one binary weight is sent to the output register 71! and this register stores a corrected combination equal to the combination registered in 707 divided by-2.
  • decoder 710 performs the third correction listed in the introductory part by shifting by a binary weight towards the right the binary number being transferred, thus dividing it by two.
  • a processor for the detection of the pitch of a speech wave for use in connection with a vocoder system comprising means for detecting the major peaks of said speech wave, means for converting said major peaks into a train of marker pulses, each pair of consecutive marker pulses of said train defining a pitch period, means for cancelling in said train each marker pulse separated from the preceding marker pulse by an interval shorter than the preceding pitch period by more than a tolerance amount, means for prohibiting the cancellation of more than a first given number of consecutive marker pulses, means for storing the value of each pitch period defined by two consecutive noncancelled marker pulses and not differing from the preceding pitch period by more than a tolerance amount, means for substituting the preceding pitch period for each pitch period differing from said preceding pitch period by more than a tolerance amount and means for prohibiting the substitution for more than a second given number of consecutive pitch periods, of the respective preceding pitch periods.
  • a processor for the detection of the pitch of a speech'wave for use in connection with a vocoder system comprising means for detecting the major peaks of said speech wave, means for converting saidmajor peaks into a train of marker pulses, each pair of consecutive marker pulses of said train defining a pitch period, means for cancelling in said train each marker pulse separated from the preceding markerpulse by an interval shorter than the preceding pitch period by more than atolerance amount, means for prohibiting the cancellation of morevthan a first given number of consecutive marker pulses, means for storing the value of each pitch period defined by two consecutive noncancelled marker pulses and not differing from the preceding pitch period by more than atolerance amount, means for.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Human Computer Interaction (AREA)
  • Computational Linguistics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Analogue/Digital Conversion (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
US00416623A 1972-11-16 1973-11-16 Pitch detection processor Expired - Lifetime US3852535A (en)

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FR7240703A FR2206889A5 (enrdf_load_stackoverflow) 1972-11-16 1972-11-16

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DE (1) DE2357067C3 (enrdf_load_stackoverflow)
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GB (1) GB1445855A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004096A (en) * 1975-02-18 1977-01-18 The United States Of America As Represented By The Secretary Of The Army Process for extracting pitch information
US4054749A (en) * 1975-12-02 1977-10-18 Fuji Xerox Co., Ltd. Method for verifying identity or difference by voice
US4063030A (en) * 1975-11-25 1977-12-13 Zurcher Jean Frederic Detection circuit for significant peaks of speech signals
US4280387A (en) * 1979-02-26 1981-07-28 Norlin Music, Inc. Frequency following circuit
US4550598A (en) * 1983-10-31 1985-11-05 The Goodyear Tire & Rubber Company Apparatus and method adapted to test tires by eliminating jitter from data signals without losing data
WO1987001498A1 (en) * 1985-08-28 1987-03-12 American Telephone & Telegraph Company A parallel processing pitch detector
US4653098A (en) * 1982-02-15 1987-03-24 Hitachi, Ltd. Method and apparatus for extracting speech pitch
US4783805A (en) * 1984-12-05 1988-11-08 Victor Company Of Japan, Ltd. System for converting a voice signal to a pitch signal
US4890328A (en) * 1985-08-28 1989-12-26 American Telephone And Telegraph Company Voice synthesis utilizing multi-level filter excitation
US4912764A (en) * 1985-08-28 1990-03-27 American Telephone And Telegraph Company, At&T Bell Laboratories Digital speech coder with different excitation types
WO1993009531A1 (en) * 1991-10-30 1993-05-13 Peter John Charles Spurgeon Processing of electrical and audio signals
US5471527A (en) 1993-12-02 1995-11-28 Dsc Communications Corporation Voice enhancement system and method
US6140568A (en) * 1997-11-06 2000-10-31 Innovative Music Systems, Inc. System and method for automatically detecting a set of fundamental frequencies simultaneously present in an audio signal
RU2174714C2 (ru) * 1998-05-12 2001-10-10 Научно-технический центр "Вычислительная техника" Способ выделения основного тона

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975587A (en) * 1974-09-13 1976-08-17 International Telephone And Telegraph Corporation Digital vocoder
DE2649259C2 (de) * 1976-10-29 1983-06-09 Felten & Guilleaume Fernmeldeanlagen GmbH, 8500 Nürnberg Verfahren zum automatischen Erkennen von gestörter Telefonsprache
US4217808A (en) * 1977-07-18 1980-08-19 David Slepian Determination of pitch
US4351216A (en) * 1979-08-22 1982-09-28 Hamm Russell O Electronic pitch detection for musical instruments
US4273023A (en) * 1979-12-26 1981-06-16 Mercer Stanley L Aural pitch recognition teaching device
US4354418A (en) 1980-08-25 1982-10-19 Nuvatec, Inc. Automatic note analyzer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974281A (en) * 1957-11-01 1961-03-07 Bell Telephone Labor Inc Selective signal recognition system
US3109142A (en) * 1960-10-06 1963-10-29 Bell Telephone Labor Inc Apparatus for encoding pitch information in a vocoder system
DE1163567B (de) * 1958-10-31 1964-02-20 E H K Kuepfmueller Dr Ing Einrichtung zur Erkennung von Sprachlauten
US3549806A (en) * 1967-05-05 1970-12-22 Gen Electric Fundamental pitch frequency signal extraction system for complex signals
US3622704A (en) * 1968-12-16 1971-11-23 Gilbert M Ferrieu Vocoder speech transmission system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974281A (en) * 1957-11-01 1961-03-07 Bell Telephone Labor Inc Selective signal recognition system
DE1163567B (de) * 1958-10-31 1964-02-20 E H K Kuepfmueller Dr Ing Einrichtung zur Erkennung von Sprachlauten
US3109142A (en) * 1960-10-06 1963-10-29 Bell Telephone Labor Inc Apparatus for encoding pitch information in a vocoder system
US3549806A (en) * 1967-05-05 1970-12-22 Gen Electric Fundamental pitch frequency signal extraction system for complex signals
US3622704A (en) * 1968-12-16 1971-11-23 Gilbert M Ferrieu Vocoder speech transmission system

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004096A (en) * 1975-02-18 1977-01-18 The United States Of America As Represented By The Secretary Of The Army Process for extracting pitch information
US4063030A (en) * 1975-11-25 1977-12-13 Zurcher Jean Frederic Detection circuit for significant peaks of speech signals
US4054749A (en) * 1975-12-02 1977-10-18 Fuji Xerox Co., Ltd. Method for verifying identity or difference by voice
US4280387A (en) * 1979-02-26 1981-07-28 Norlin Music, Inc. Frequency following circuit
US4653098A (en) * 1982-02-15 1987-03-24 Hitachi, Ltd. Method and apparatus for extracting speech pitch
US4550598A (en) * 1983-10-31 1985-11-05 The Goodyear Tire & Rubber Company Apparatus and method adapted to test tires by eliminating jitter from data signals without losing data
US4783805A (en) * 1984-12-05 1988-11-08 Victor Company Of Japan, Ltd. System for converting a voice signal to a pitch signal
WO1987001498A1 (en) * 1985-08-28 1987-03-12 American Telephone & Telegraph Company A parallel processing pitch detector
US4879748A (en) * 1985-08-28 1989-11-07 American Telephone And Telegraph Company Parallel processing pitch detector
US4890328A (en) * 1985-08-28 1989-12-26 American Telephone And Telegraph Company Voice synthesis utilizing multi-level filter excitation
US4912764A (en) * 1985-08-28 1990-03-27 American Telephone And Telegraph Company, At&T Bell Laboratories Digital speech coder with different excitation types
WO1993009531A1 (en) * 1991-10-30 1993-05-13 Peter John Charles Spurgeon Processing of electrical and audio signals
US5471527A (en) 1993-12-02 1995-11-28 Dsc Communications Corporation Voice enhancement system and method
US6140568A (en) * 1997-11-06 2000-10-31 Innovative Music Systems, Inc. System and method for automatically detecting a set of fundamental frequencies simultaneously present in an audio signal
RU2174714C2 (ru) * 1998-05-12 2001-10-10 Научно-технический центр "Вычислительная техника" Способ выделения основного тона

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FR2206889A5 (enrdf_load_stackoverflow) 1974-06-07
GB1445855A (en) 1976-08-11
DE2357067C3 (de) 1979-08-09
DE2357067A1 (de) 1974-05-30
DE2357067B2 (de) 1978-12-07

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