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Multi-feature speech/music discrimination system
2010-03-29 00:00:00
signal into a plurality of frequency bands;

determining modulation frequencies of the audio signal in each band;

identifying the amount of correspondence of the modulation frequencies among the frequency bands; and

classifying whether audio signal has musical content in dependence upon the identified amount of correspondence;

wherein the step of determining the modulation frequencies in a frequency band comprises the steps of:

determining an energy envelope of the frequency band;

identifying peaks in the energy envelope; and

calculating a windowed autocorrelation of the peaks.

13. A method for determining whether an audio signal contains music content, comprising the steps of:

dividing the audio signal into a plurality of frequency bands;

determining modulation frequencies of the audio signal in each band;

identifying the amount of correspondence of the modulation frequencies among the frequency bands; and

classifying whether audio signal has musical content in dependence upon the identified amount of correspondence;

wherein the step of identifying the amount of correspondence of the modulation frequencies comprises the steps of:

determining peaks in the modulation frequencies for each band;

selecting a first pair of frequency bands;

counting the number of modulation frequency peaks which are common to both bands in the selected pair; and

repeating said counting step for all possible pairs of frequency bands.

14. A method for discriminating between speech and music content in audio signals that are divided into successive frames, comprising the steps of:

selecting a set of audio signal samples;

measuring values of a feature for individual frames in said samples;

determining the variance of the measured feature values over a series of frames in said samples;

defining a multi-dimensional feature space having at least one dimension which pertains to the variance of feature values;

defining a decision boundary between speech and music in said feature space;

measuring a feature value for a test sample of an audio signal and a variance of a feature value, and determining a corresponding data point in said feature space; and

classifying the test sample in accordance with the location of said corresponding point relative to said decision boundary.

15. The method of claim 14 wherein said classifying step comprises determining whether a data point in said feature space which is nearest to the data point for said test sample pertains to speech or music.

16. The method of claim 14 wherein said classifying step comprises the steps of identifying a plurality of data points which are nearest to the data point for said test sample, and labelling said test sample as speech or music in accordance with whether a majority of the identified data points pertain to speech or music.

17. The method of claim 14 wherein said decision defining step comprises the steps of dividing the feature space into regions in accordance with measured features and variances, and labelling each region as relating to speech data or music data, and said classifying step includes determining the region in said feature space in which the data point for said test sample is located.

18. A method for detecting speech content in an audio signal, comprising the steps of:

selecting a set of audio signal samples;

measuring values for a plurality of features in samples of said set of samples;

defining a multi-dimensional feature space containing data points which respectively correspond to the measured feature values for each sample, and labelling whether each data point relates to speech;

measuring feature values for a test sample of an audio signal and determining a corresponding data point in said feature space;

determining the label for at least one data point in said feature space which is close to the data point corresponding to said test sample; and

indicating whether the test sample is speech in accordance with the determined label.

19. The method of claim 18 wherein said determining step comprises determining the label for the data point in said feature space which is nearest to the data point for said test sample.

20. The method of claim 18 wherein said determining step comprises the steps of identifying a plurality of data points which are nearest to the data...

Control system for a musical instrument
2010-03-09 00:00:00
program function 606. The controller 300 then determines in decision state 536 whether the program button 216 has been depressed again by the musician 100. The musician 100 depresses the program button 216 again when he wants to program the initial volume characteristic. Once the musician had depressed the button 216, the controller 300 proceeds to state 636 wherein it causes the program LED 214 (FIG. 4) to flicker red at a fast rate. This informs the musician 100 that the initial volume characteristic is ready to be programmed.

The initial volume characteristic is programmed by the musician playing the instrument 102 and exerting pressure on the tactile member 106 causing the sensor 320 (FIG. 5) to send an appropriate signal to the controller 300 in state 640. The controller 300 then adjusts the volume characteristic in state 642, to correspond to the pressure input signal, by sending an appropriate signal to the signal modifier 330 (FIG. 5). This characteristic is then applied to the audio signal produced by the musical instrument 102 so that the musician 100 can hear the volume characteristic of the audio signal.

When the volume characteristic is acceptable to the musician 100, the musician manipulates the program switch 214 causing the controller 300 to record, in state 646, the initial volume characteristic in the memory 330. The controller 300 then determines whether the programming of the volume has ended in decision state 650. The program volume function 606 ends when the musician leaves the program mode or turns the device off causing the controller 300 to enter an end state 652.

Hence, the program volume function 606 enables the musician to set an initial volume characteristic of the audio signal by playing the musical instrument 102 and then setting the initial volume characteristic at a desired amount based upon what the musician hears.

FIG. 12 is a flow chart which illustrate the steps performed by the controller 300 when it executes the program tremolo function 612 (FIG. 10). From a start state 680, the controller 300 initially proceeds to read the frequency and amplitude presets for the tremolo characteristic in state 682. When programming a tremolo characteristic, the musician 100 enters the program mode and then simultaneously depresses the speed and depth preset buttons 218, 220 (FIG. 4). This induces the controller 300 to enter the program tremolo function mode. The musician 100 can then select which of the three preset positions for each of these buttons 218, 220 are to be programmed.

Once the musician 100 has selected the presets to program, the controller 300 then sets in state 684 the frequency component and the amplitude component of the tremolo characteristic at the preset values. In the preferred embodiment, there are pre-existing preset values always programmed into the control system 104 which are either previously programmed values entered by the musician 100 or default values entered at the factory. Hence, in state 684, a tremolo characteristic is produced that will be used to modify the audio signal produced by the musical instrument 102 while the musician 100 is playing the musical instrument 102 to program a new desired tremolo characteristic. The controller 300 then induces the LEDs 218a, 220a in both the speed and the depth buttons 218, 220 to flash in state 685 to signify to the musician 100 that the control system 104 is in the tremolo program mode. As discussed above, in the program mode the LEDs are preferably programmed to flash at a rate which also indicative of the preset position of the buttons 218, 220.

The controller 300 then determines in decision state 686 which component of the tremolo characteristic, i.e., speed or depth, that the musician is intending to program. In the preferred embodiment, the controller 300 is initially set to program the frequency or speed component, however, if the musician 100 depresses the volume button 216 (FIG. 4), the controller 300 will toggle to the depth or amplitude component. Repeatedly depressing the volume button will cause the controller 300 to toggle between these two components.

Assuming that the controller 300 has determined in decision state 686 that the musician 100 wishes to program the frequency component, the controller 300 then determines in decision state 692 whether the musician 100 has manipulated the program mode select button 212 (FIG. 4) to begin programming the selected frequency preset. The controller 300 continues to flash the frequency LED at a rate corresponding to the preset until the controller 300 receives an input from the program mode select button 212 indicating that the musician 100 has manipulated the button.

The controller 300 then induces the program LED 214 to flicker in state 694 which provides an indication to the musician 100 to begin programming the frequency component for the selected preset. The musician 100 does this by playing the musical instrument 102 to produce an audio signal and then exerting pressure on the tactile member 106 to cause the frequency of the tremolo effect induced on the audio signal to change. Hence, the controller 300 in state 696 reads the pressure input from the sensor 320 (FIG. 5) and adjusts the tremolo frequency component in state 700 accordingly. The controller 300 continues to adjust the frequency component in accordance with the amount of pressure the musician is exerting on the tactile member 106 until the musician 100 manipulates the program button 212 (FIG. 4). This again induces the controller 300 to record in state 704 the frequency value in the memory 330 and the controller 300 then changes the program LED 214 back to solid in state 706.

Hence, the musician programs a frequency component for a selected preset position of the button 218 by entering the program mode, playing the instrument 102, depressing the tactile member 106 to change the frequency and then depressing the program button 212 to record the new desired frequency component for this preset. In the preferred embodiment, there are three separate presets that the musician 100 can program in the previously described manner.

Once the programming of the selected frequency preset has been completed, the controller 300 then determines whether the tremolo programming function 612 has en...

Electronic music system and stringed instrument input device therefor
2010-03-02 00:00:00
value analogously related to the frequency of the musical tone assigned to the contacting string-fret pair, said voltage controlled tone generator including means forproducing an intermediate signal having a frequency related to said input voltage signal, an amplifier having a voltage controlled gain for varying the amplitude of said intermediate signal, an envelope generator for providing a voltage waveformcontrolling the gain of said amplifier, and means for turning said envelope generator on to initiate the production of a new voltage waveform therefrom in response to said at least one string being brought into contact with any one of said frets.

2. An electronic music system comprising a voltage controlled tone generator, a stringed instrument having a plurality of spaced parallel strings located over a fret board having a plurality of frets extending transversely of said strings andspaced one from another along the length of said fret board with each string-fret pair representing an assigned musical tone, and means responsive of any one of said strings being pressed into contact with any one of said frets for producing andsupplying to said voltage controlled tone generator, as the driving input for said tone generator, a voltage signal having a voltage value analogously related to the frequency of the musical tone represented by the contacting string-fret pair.

3. A music system as defined in claim 2 further characterized by said voltage controlled tone generator including means for producing an intermediate signal having a frequency related to said input voltage signal, an amplifier having a voltagecontrolled gain for varying the amplitude of said intermediate signal, an envelope generator for producing a voltage waveform controlling the gain of said amplifier, and means for turning said envelope generator on to initiate the production of a newvoltage waveform therefrom in response to any one of said strings being brought into contact with any one of said frets.

4. A music system as defined in claim 3 further characterized by means for inhibiting the production of another voltage waveform from said envelope generator until after all of said strings are first out of contact with any of said frets.

5. An electronic music system comprising a voltage controlled tone generator, a stringed instrument having a plurality of spaced parallel strings and a plurality of frets spaced from one another along the length of said strings and eachextending transversely across all of said strings with each string-fret pair representing an assigned musical tone, and means responsive to any one or more of said strings being pressed into contact with any one or more of said frets for producing andsupplying to said voltage controlled tone generator, as the driving input signal for said tone generator, a voltage signal having a voltage value analogously related to the frequency of the highest musical tone represented by the contacting string-fretpair or pairs.

6. An electronic music system as defined in claim 5 further characterized by said means for producing a voltage signal including means for applying a discrete voltage to each of said frets and which discrete voltage is different from thatapplied to other of said frets, an offset voltage source providing a plurality of offset voltages each assigned to a respective one of said strings and each of which offset voltages is different from the other of said offset voltages, and meansresponsive to any one of said strings being pressed into contact with any one of said frets for adding the voltage appearing on said one fret to the offset voltage assigned to said one string to produce a resultant voltage signal analogously related tothe tone represented by the contacting string-fret pair.

7. An electronic music system comprising a voltage controlled tone generator, a stringed instrument having a plurality of spaced parallel electrically conductive strings and a plurality of electrically conductive frets spaced from one anotheralong the len...

Generation of noise-like tones in an electronic musical instrument
2010-02-27 00:00:00
analog or digital circuits, is well known. In attempting to duplicate the sounds of conventional musical instruments it may be desirable to superimpose sounds which can only becharacterized as "noise" onto the musical tones. Such added noise may be introduced to simulate the air noise, hiss, or breathiness characteristic of wind-operated instruments, such as the organ pipes of a conventional organ, or other types of windinstruments. In prior art digital type organs tones have been created imitative to noisy wind-blown organ pipes, by using a frequency modulation technique. This has been accomplished by adding or subtracting a fixed constant to the frequency numberused to address the tone data. Alternatively, the noise has been added to the reference voltage of the analog output signal from the digital-to-analog converter to produce an amplitude modulated noise. Noiselike tones have been created in digital tonegenerators by the type which calculate musical waveshapes by computation with an algorithm that uses sets of harmonic coefficients. However, the resulting tonal effect is not easily controlled. If the harmonic coefficients are varied in a randomfashion, noise having a very wide spectrum is produced and has the effect of substantially obliterating the basic musical tone being generated.

SUMMARY OF THE INVENTION

In copending application Ser. No. 603,776, filed Aug. 11, 1975, entitled "Polyphonic Tone Synthesizer", now issued as U.S. Pat. No. 4,085,644 there is described a digital tone generator in which a master data list is calculated and stored ina main register. The master data list consists of a series of digital values representing the amplitudes of a corresponding series of points defining the waveform of one cycle (or fraction of a cycle) of a musical tone. The master data list istransferred from the main register to a Note shift register and from the Note register to a digital-to-analog converter at a rate determined by the pitch or fundamental frequency of the tone being generated. Because the pitch is controlled independentlyof the amplitude values in the master data list, any set of numbers stored in the Note shift register will produce a musical tone having a controlled fundamental frequency determined by t...

Electronic musical instrument with exponential keyboard and voltage controlled oscillator
2010-02-26 00:00:00
at a frequency corresponding to that associated with a depressed key of the keyboard. The key selects a control voltage, from an exponential voltage divider, for controlling the frequency of a voltage controlled oscillator, which produces a frequency which is directly proportional to the control voltage and inversely proportional to a reference voltage. The reference voltage compensates for variations in the level of the supply voltage, so that the oscillator frequency is independent of the supply voltage.ClaimsWhat is claimed is:

1. An electronic musical instrument having a voltage controlled oscillator for producing a sound signal having a frequency proportional to a control voltage applied to it, akeyboard having a plurality of keys, a plurality of switches, one for each of said keys, each adapted to be operated by depression of its associated key, and a voltage divider connected with said switches for connecting a control voltage to saidoscillator which corresponds to the position of the key associated with an operated one of said switches, said voltage divider comprising a plurality of resistance elements connected in series, each of said elements having different resistance valueswhich bear an exponential relation to the resistance values of the adjacent connected resistors such that the voltage at successive junctions of said resistance elements correspond to a geometric series, said resistance elements being formed of the samematerial and being physically located in close physical juxtaposition with each other, so that all said resistors are maintained at approximately the same temperature, with approximately constant relative resistances.

2. Apparatus according to claim 1 wherein said resistance elements are formed simultaneously as portions of a single integrated thick-film circuit.

3. In an electronic musical instrument having an electrical power supply, a voltage controlled oscillator for producing a sound signal having a frequency proportional to a control voltage applied to it, a keyboard having a plurality of keys, aplurality of switches, one for each of said keys, each adapted to be operated by depression of its associated key, and connecting means connected with said switches for connecting a control voltage to said oscillator which corresponds to the position ofthe key associated with an operated one of said switches, the combination comprising a reference voltage generator connected to said electrical power supply for producing a reference voltage, and means connecting said oscillator to said reference voltagegenerator, said reference voltage generator being adapted to produce a shift in the level of said reference voltage in response to a change in the level of voltage of said electrical power supply, said shift having a magnitude and direction tending tocompensate for said change in power supply voltage level, whereby said oscillator frequency is substantially independent of said change.

4. Apparatus according to claim 3, wherein said reference voltage generator comprises an inverter having an input connected with said power supply.

5. Apparatus according to claim 4, wherein said oscillator comprises an integrator for integrating a voltage derived from said voltage divider, a comparator connected to said integrator and operative to compare an output produced by saidintegrator with said reference voltage, and means connected with said comparator and operative upon a comparison of said integrator output and said reference voltage for resetting said integrator for a subsequent cycle of integration.

6. An electronic musical instrument having a voltage controlled oscillator for producing a sound signal having a frequency proportional to a control voltage applied to it, a keyboard having a plurality of keys, a plurality of switches, one foreach of said keys, each adapted to be operated by depression of its associated key, a voltage divider connected with said switches for connecting a control voltage to said oscillator which corresponds to the position of the key associated with anoperated one of said switches, said voltage divider comprising a plurality of resistance elements connected in series, each of said elements having resistance value...

Electronic musical instrument with means for automatically generating chords and harmony
2010-02-05 00:00:00
Apparatus according to claim 9, wherein each of said generators comprises a programmable frequency synthesizer having a read only memory, addressing means for said read only memory, and a programmable divider connected to said read onlymemory, means for connecting said storage means to said addressing means for addressing a section of said read only memory corresponding to the representation stored in said storage means, said divider being programmed by signals produced by said readonly memory in accordance with signals supplied to said addressing means, and means for connecting said programmable divider to a source of clock pulses, whereby said programmable divider produces an output signal having a frequency which is a quotientof the frequency of said clock pulses.

11. Apparatus according to claim 9, including a decoder connected to said storage means for producing an individual signal on one of a plurality of output lines corresponding to the note name, the representation of which is stored in saidstorage means, each of said generators having a plurality of input terminals connected in common to said plurality of output lines, and each of said generators being adapted to respond to a single energized one of said plurality of output lines toproduce a tone signal having an individual frequency.

12. Apparatus according to claim 1, including a plurality of divider units, one for each of said tone signal generators, said divider units being connected between each of said tone signal generators and said output system, manifesting means formanifesting a representation of the note name of a key corresponding to a pulse of said pulse train, means for connecting said manifesting means to said storage means to cause said storage means to store said representation, and means connecting saidstorage means with said divider units for controlling the operation of said divider units in accordance with said representation.

13. Apparatus according to claim 1, wherein two of said generators simultaneously produce two tone signals corresponding to two different keys of the keyboard which are simultaneously depressed.

14. Apparatus according to claim 1, wherein said signal producing means includes means for identifying a single operated key of said keyboard and means reponsive to said last named means for operating all of said generators.

15. Apparatus according to claim 14, wherein said last named means causes said generators to produce tone signals corresponding to the root, third and fifth of a selected chord, said tone signals each being produced by a separate one of saidgenerators.

16. Apparatus according to claim 15, including means for causing one of said generators for producing a tone signal corresponding to the seventh of said selected chord, and means responsive to one of said function selecting switches forselectively producing an output signal containing said tone signal corresponding to the seventh of the chord.

17. Apparatus according to claim 15, including means responsive to one of said function selecting switches for selectively causing one of said generators to produce a tone signal corresponding to the minor third of said selected chord.

18. Apparatus according to claim 15, including strum means responsive to one of said function selecting switches for causing said tone signals to be produced at an output terminal successively in predetermined order.

19. Apparatus according to claim 18, including a plurality of tone signal output terminals, a plurality of gates for connecting individual ones of said generators to said output terminals when said one function selecting switch is closed, aplurality of keying signal output terminals, and means for providing pulses sequentially to said keying signal output terminals.

20. Apparatus according to claim 19, wherein said last named means comprises a clock signal generator, a plurality of gates each having an output connected to one of said keying signal output terminals, and pulse distributing means forsuccessively applying pulses from said clock signal generator to said keying signal output terminals.

21. Apparatus according to claim 20, including bistable means, means for connecting an input pulse to said bistable means for setting said bistable means to a first state, means connecting said bistable means to said pulse distributing means forinitiating operation of said pulse distributing means, and means for resetting said bistable means at the end of one cycle of pulses applied to said keying signal output terminals.

22. Apparatus according to claim 21, including means for selectively producing at one of said tone signal output terminals a tone signal corresponding to the seventh of a selected chord, and a corresponding signal at one of said keying signaloutput terminals, and means for resetting said bistable means following production of said corresponding signal.

23. Apparatus according to claim 21, including means for resetting said pulse distributing means with said bistable means, whereby said strum output means initiates each cycle of operation with production of a pulse at the same keying signaloutput terminal.

24. Apparatus according to claim 14, including a tone signal output terminal, and means for sequentially connecting individual ones of said tone signal generators to said tone signal output terminal in ascending and descending order, relative tothe pitches of said tone signals which are connected to said tone signal output terminal.

25. Apparatus according to claim 24, including multiplexer means for connecting said generators one at a time to said tone signal output signal, a bistable device, means for sequencing said multiplexer means in ascending order when said bistabledevice is in one state and for sequencing said multiplexer means in descending order when said bistable device is in its other state, and means for alternately setting and resetting said bistable device, respectively, when the highest and lowest pitchesof said tone signals are connected to said tone signal output terminal.

26. Apparatus according to claim 25, including means for selectively resetting the sequencing means for said multiplexer means...