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Multi-feature speech/music discrimination system
2010-03-29 00:00:00
The method of claim 1 wherein said determining step comprises the steps of identifying a plurality of data points which are nearest to the data point for said test sample, and selecting the label which is associated with a majority of the identified data points.

4. The method of claim 1 wherein said determining step comprises the steps of dividing the feature space into regions in accordance with said features, labelling each region as relating to speech data or music data in accordance with the labels for the data points in the region, and determining the region in said feature space in which the data point for said test sample is located.

5. The method of claim 1 wherein one of said features is the variation of spectral flux among a series of frames of the audio signal.

6. The method of claim 1 wherein one of said features is a pulse metric which identifies correspondence of modulation frequency peaks in different respective frequency bands of the audio signal.

7. The method of claim 1 wherein one of said features is measured by the steps of determining the mean power for a series of frames of said audio signal, and determining the proportion of frames in said series whose power is less than a predetermined fraction of said mean power.

8. The method of claim 1 wherein one of said features is the proportion of energy in the audio signal having speech modulation frequencies.

9. The method of claim 8 wherein said speech modulation frequencies are around 4 Hz.

10. The method of claim 1 wherein said audio signal is divided into a sequence of frames, and wherein values for some of said features are measured for individual frames, and values for others of said features relate to variations of measured values over a series of frames.

11. The method of claim 1 wherein said audio signal is divided into a sequence of frames and further including the steps of classifying each frame of the test sample as relating to speech or music, examining the classifications for a plurality of successive frames, and determining a final classification on the basis of the examined classifications.

12. 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 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 i...

Musical scale indicator
2010-03-26 00:00:00
tonic being selected for each said pre-selected music scale, said step of aligning further providing a fingering pattern for each said pre-selected music scale in its said respective tonic.

13. The method for finding tones playable on a musical instrument of claim 12, wherein the first step of placing provides fingering indicia and the second step of placing provides simulated fingering board indicia for a pre-selected musical instrument selected from the group consisting of string instruments, brass and woodwind instruments and percussion instruments.

14. The method for finding tones playable on a musical instrument of claim 13, wherein the first step of placing provides fingering indicia and the second step of placing provides simulated fingering board indicia for a pre-selected musical instrument selected from the group consisting of guitar, alto-saxophone and piano.DescriptionBACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a device for indicating musical notes playable in any musical scale; more particularly, the present invention is an indicator for musical notes playable in any musical scale with said notes being visually associated with the finger boards used to play selected musical instruments.

2. Description of the Prior Art:

A. Basic Music Theory, Tonality, Musical Scales, and Musical Instruments

There are many different styles of music. But, every style of music is based upon a predetermined progression of tones. Tones, or notes, are variations in pitch (sound frequency) produced by a musical instrument. It has become customary to refer to these tones by seven letter designations: A, B, C, D, E, F, and G. When these tones, or notes, repeat, as in A B C D E F G A, then the interval between the first and last tones is known as an octave. The sound frequency difference between tones is given in "steps", and the steps between each of the tones A, B, C, D, E, F, and G is not the same. There is a half-step interval between tones B and C, and between tones E and F, while there are whole-step intervals between A and B, C and D, D and E, and F and G. Each tone may be raised or lowered one-half step; these are known as the accidentals of the tone, and they are represented by a "鈾? sign for "sharps", which raise the tone one-half step, and represented by a "b" sign for "flats", which lower the tone one-half step. The Chromatic Scale, from which all music derives, is based upon the natural tones, A, B, C, D, E, F, and G (the white piano keys), as well as upon the accidentals F鈾? G鈾? A鈾疌鈾?and D鈾?(the black piano keys).

In any melody, there is one tone which seems to dominate and be more final than any other tone. If a musical melody is played without finishing on this tone, the melody appears to the ear as somehow incomplete. This central tone is called the "tonic", or "key ". Each tonic has a set of tones which are related to it in varying degrees. When a musical score begins on a certain tone, it can be expected that certain selected tones will follow. These groups of tones, which relate to the concept of "tonality", constitute the musical "scales".

Over the years a number of musical scales have been developed, as follows.

By the seventeenth century, the following scales (or modes) were in use:

A B C D E F G A ... known as Aeolian;

B C D E F G A B ... known as Locrian;

C D E F G A B C ... known as Ionian;

D E F G A B C D ... known as Dorian;

E F G A B C D E ... known as Phrygian;

F G A B C D E F ... known as Lydian; and

G A B C D E F G ... known as Mixolydian.

The Major scale, like Ionian Mode, is based upon a succession of eight tones modeled on the tone intervals, or steps, when the succession of tones begins on C. These intervals are: C-D, D-E, E-F, F-G, G-A, A-B, and B-C; constituting steps which ar...

Low profile keyboard device and system for recording and scoring music
2010-03-23 00:00:00
electrical analog output signals from a key's electrical analog output signal providing means to determine if the amount of key depression haschanged and means for generating note expression data representative of key strike and release velocity for such key in response to changes in consecutive electrical analog output signals from its associated electrical analog output signal providingmeans.

7. The apparatus of claim 4 further comprising means for converting said data representative of the live musical performance to a form transferable to a computer compatible link.

8. The apparatus of claim 1 wherein said light emitting means comprises a light emitting diode for each covered key.

9. The apparatus of claim 8 wherein said electrical analog output signal providing means comprises, for each covered key, a phototransistor.

10. The invention of claim 1 in combination with at least a second said modular apparatus and means for operatively connecting said modular apparatuses.

11. The invention of claim 10 wherein each said modular apparatus comprises an encodable module identifying means.

12. The invention of claim 10 wherein each said modular apparatus is an octave module comprising a housing operatively covering twelve keys.

13. The apparatus of claim 1 comprising means for varying the light intensity to each light emitting means to compensate for differences in reflectivity for individual keys on said keyboard.

14. A method for acquiring data representative of a performance on a keyboard instrument comprising:

for each key within a selected group of keys on the keyboard instrument,

(a) emitting light from a source,

(b) impinging the light onto the key,

(c) reflecting the light from the key onto a photodetector in accordance with the amount the key is depressed to generate an electrical analog output signal indicative of the amount of key depression,

using steps (a), (b), and (c), in accordance with a clock signal, sequentially initiating the electrical analog ouput signal for each key within the group of keys sufficiently frequently to provide a series of electrical analog output signalsrepresentative of key depression as a function of time, comprising key striking and release velocities.

monitoring the series of electrical analog output signals for each key to acquire data representative of the performance, and

comparing the strengths of consecutive electrical analog output signals within the series from each key within the group of keys to determine if a change in the amount of depression for each key has occurred and generating note expression datarepresentative of key strike and release velocity when the signal strength comparison step indicates a change in key depression has occurred for a key.

15. The method of claim 14 further comprising adjusting the amount of light impinging on each key to compensate for differences in reflectivity for each key.

16. The method of claim 14 wherein the clock signal is sufficiently fast to provide accurate data for key strike and release velocities.

17. The method of claim 14 further comprising converting the acquired data into a form transferable to a computer compatible link.DescriptionBACKGROUND OF THE INVENTION

This invention relates to a convenient, low cost modular device to be unobtrusively attached to any keyboard instrument which electronically captures musical note and note expression data; and a processing system to convert and transmit the datato computer-compatible interfaces thereby recording live musical performances.

Various inventions have been devised to assist musicians in performing, arranging, recording and composing music. An historically early method of recording music which is still in use today is the player piano. Holes, corresponding toparticular notes, are punched in paper which is rotated as the player piano is played. Recording music with this technique requires an entirely different instrument than the piano or substantial adjustments to a conventional piano. U.S. Pat. No.1,194,302, entitled "MUSIC RECORDER," to Liefield, discloses an extremely bulky electrical attachment which is capable of recording musical notes on a rotating sheet of paper to be applied to a conventional keyboard instrument. The device of thisinvention which attaches to the keyboard, however, covers more than half of the keyboard and thus interferes with a musician's efforts at the keyboard. U.S. Pat. No. 4,351,221, entitled, "PLAYER PIANO RECORDING SYSTEM," to Starnes et al, teaches amore modern recording system in which player piano tapes are prepared. This system requires the elaborate and delicate installation of photosensors to the underside of the piano keys. While the invention does not interfere with the musician's use ofthe keyboard, such installation of the apparatus to the keyboard is expensive and requires the services of a skilled piano tuner or electronics technician. This invention is furthermore limited in its application because the purpose of the invention isto create player piano tapes and not a musical score for immediate viewing by the musician. Another example of a musical recording system is given in U.S. Pat. No. 3,798,719, entitled "TAPE ACTIVATED PIANO AND ORGAN PLAYER," to Maillet, which...

Wavetable-modification instrument and method for generating musical sound
2010-03-12 00:00:00
the pitch number N for each voice to the Write Pointer to provide the Read Pointer for each voice.

21. The instrument of claim 20 wherein the wavetable is a random access memory, wherein the stored data value for each voice is stored in said memory at a Write Pointer address unique to that corresponding voice and wherein the delayed datavalues are stored in memory locations determined by a Read Pointer address for each voice and wherein said Write Pointer and Read Pointer addresses for each voice are offset by a number equal to the pitch number, N for each voice.

22. The instrument of claim 21 wherein the Write Pointer address includes a low-order field for uniquely identifying each different voice and includes a high-order field for identifying the location within a portion of the memory associated withthe voice identified in the corresponding low-order field.

23. The instrument of claim 22 wherein said generator includes means for decrementing said Write Pointer each time a data value is stored at the location specified by said Write Pointer.

24. The instrument of claim 23 wherein the sampling frequency, fs, is the same for each voice.

25. The instrument of claim 24 including means for providing said data values at a logic cycle frequency which is the number of voices times fs.

26. The instrument of claim 25 wherein the output unit includes a digital-to-analog converter for receiving each new data value for each voice and includes a low pass filter for filtering the analog value from said converter and wherein saidconverter receives a new data value at said logic cycle frequency whereby the output from said low pass filter is a signal representing the musical sound for all of the voices.

27. The instrument of claim 18 including means for storing a Write Pointer and means for storing a Read Pointer for each voice, said Write Pointer having an address offset from said Read Pointer for each voice by the pitch number N for eachvoice, respectively, and including means for updating both said Write Pointer and said Read Pointer concurrently for each voice whereby the offset N between the Read Pointer and the Write Pointer for each voice is maintained.

28. A musical instrument for producing musical sound comprising,

input means for specifying a musical sound to be generated,

wavetable-modification generator means for generating by wavetable modification an output signal representing the musical sound to be produced, including a wavetable unit for cyclically storing data values for a delay period defined by a pitchnumber N, including a modifier unit for combining two or more delayed data values from said wavetable unit to form a modified data value, and including selection means for selecting the modified data value or a delayed data value stochastically basedupon a predetermined probability as a stored value stored back into the wavetable unit for subsequent delay by the period N where the stored value forms the output signal,

an output unit responsive to said output signal to produce the musical sound.

29. The instrument of claim 28 wherein said predetermined probability equals unity whereby the stored value is always the modified data value, and has an amplitude yn at a sample time n where yn is given as follows,

where yn-N is the data value output from the wavetable after delay of N and where yn-(N 1) is the data value output from the wavetable after a delay of N 1 and where xn is an input data value at sample time n having a signalamplitude initially loaded into the wavetable.

30. The instrument of claim 29 including means for storing the modified data value, yn, in said memory at a Write Pointer address, including means for storing the data value yn-N in said memory at a Read Pointer address, includingmeans for storing the data value yn-(N 1) in said memory at a Read Pointer 1 address which is offset from said Read Pointer address by 1 and wherein said Write Pointer address and said Read Pointer address are offset by a number of addresses equalto the pitch number N.

31. The instrument of claim 30 wherein said values of xn represent white noise and are given as follows:

where un is determined as 1 or -1 as a function of the output of a random number generator and where A is some amplitude....

Method for encoding music printing information in a MIDI message
2010-03-10 00:00:00
in Europe), can alternatively be spelled F4-#-#-鈾?鈾? G4-鈾?鈾? A4, B4-鈾?鈾? C5-鈾?鈾?鈾? D5-鈾?鈾?鈾?鈾?鈾? In "real-life" situations, it is rare to find more than two sharps or flats attached to a primary degree (note letter).

MIDI representation of pitch.

The Musical Instrument Digital Interface (MIDI) standard for representing musical events developed originally as a convention for communicating between electronic instruments. Since the primary (and musically most sophisticated) electronic instrument was the music (piano) keyboard, a system was devised to represent all possible (musically "likely") keys on the keyboard. The note, middle C, normally designated C4, was assigned the number 60. Each successive key above C4 was assigned a successively higher integer, and each successively lower key was assigned a successively lower integer. This system has served its original purpose well, since each note (key) on the keyboard has one and only one number associated with it.

The Problem with MIDI and the printing of music

The MIDI Interface

The MIDI system is well known. A wide variety of instruments and MIDI-compatible devices have been patented. For a good general background on the MIDI system, see U.S. Pat. No. 5,208,421 by Lisle et al, a portion of which is reproduced here.

MIDI was established as a hardware and software specification which would make it possible to exchange information such as: musical notes, program changes, expression control, etc. between different musical instruments or other devices such as: sequencers, computers, lighting controllers, mixers, etc. This ability to transmit and receive data was originally conceived for live performances, although subsequent developments have had enormous impact in recording studios, audio and video production, and composition environments.

A standard for the MIDI interface has been prepared and published as a joint effort between the MIDI Manufacturer's Association (MMA) and the Japan MIDI Standards Committee (JMSC). This standard is subject to change by agreement between JMSC and MMA and is currently published as the MIDI 1.0 Detailed Specification, Document Version 4.1, January 1989. Various revisions and extensions of this system have been described in the literature but the basic standard is still followed.

The hardware portion of the MIDI interface operates at 31.25 KBaud, asynchronous, with a start bit, eight data bits and a stop bit. This makes a total of ten bits for a period of 320 microseconds per serial byte. The start bit is a logical zero and the stop bit is a logical on...

Control system for a musical instrument
2010-03-09 00:00:00
of three pre-set amplitudes.

From the foregoing, it is apparent that the control system of the preferred embodiment enables the musician to program preset volume levels, tremolo frequency levels and tremolo amplitude levels by simply playing the instrument and exerting pressure on the tactile member. Subsequently, the musician can select between the preset levels while playing the instrument. The musician can also use the tactile member while playing the instrument to dynamically adjust the volume of the audio signal and the frequency of a tremolo effect applied to the audio signal by exerting pressure on the tactile member. Hence, the control system affords the musician greater flexibility in adjusting the characteristics of the audio signal produced by the musical instrument.

These and other objects and features of the present invention will become more fully apparent from the following description and appended claims take in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a musical instrument used in conjunction with a first embodiment of a control system of the present invention;

FIG. 2 is a perspective view of the musical instrument shown in FIG. 1, used in conjunction with a second embodiment of a control system of the present invention;

FIGS. 3A and 3B are partially cut-away perspective views of a tactile member which forms a portion of the control system shown in FIGS. 1 and 2;

FIG. 4 is a perspective view of a control box, and the external controls associated therewith, comprising a portion of the control system of the present invention.

FIG. 5 is an electrical schematic which illustrates a control circuit which forms a portion of the control system shown in FIGS. 1 and 2;

FIG. 6 is a flow chart illustrating the operation of the control circuit shown in FIG. 5;

FIG. 7 is a flow chart illustrating the operation of the control circuit as it performs an operation function shown in FIG. 6;

FIG. 8 is a flow chart illustrating the operation of the control circuit as it performs a volume operation function shown in FIG. 7;

FIG. 9 is a flow chart illustrating the operation of the control circuit as it performs a tremolo operation function shown in FIG. 7;

FIG. 10 is a flow chart illustrating the operation of the control circuit as it performs a program function shown in FIG. 6;

FIG. 11 is a flow chart illustrating the operation of the control circuit as it performs a program volume function illustrated in FIG. 10; and

FIGS. 12 and 12A is a flow chart illustrating the operation of the control circuit as it performs a program tremolo function shown in FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like numerals refer to like parts throughout. FIGS. 1 and 2 illustrate a musician 100 holding a musical instrument 102, which in this case is an electric guitar. The musical instrument 102 is equipped with a music control system 104 of the preferred embodiment.

The music control system 104 includes one or more flexible tactile members 106 that are positioned on the musical instrument 102. The flexible tactile members 106 are preferably positioned on the musical instrument 102 in places where the musician 100 can exert pressure on the flexible tactile members 106 without the musician 100 removing his hands from playing positions on the musical instrument 102. In this embodiment, the tactile member 106 is positioned adjacent the neck of the guitar where the musician 100 can press down in the tactile member 106 with either his thumb or finger. Alternatively, the tactile member 106 could have been positioned adjacent the musician's strumming hand (shown in phantom) thereby allowing the musician 100 to use his strumming hand to exert pressure on the tactile member 106.

In the preferred embodiment, the tactile member 106 is a sealed air hose that the musician 100 can depress to thereby change the pressure within the air hose. The tactile member 106 is connected to a central control box 108 that has a sensor which determines the extent to which the musician has depressed the tactile member 106.

FIG. 2 illustrates a second embodiment of the invention wherein the tactile members 106 all are connected to a central manifold 110. The central manifold 110 is preferably connected to the central control box 108 via a connecting member 112. In the preferred embodiment, the connecting member 112 is a pressure hose which transmits the pressure from the tactile members 106 to the control box 108. The central manifold 110 is preferably selectable so that the musician 100 can select which of the plurality of tactile members 106 that is going to be used to transmit signals to the control box 108. Hence, the central manifold 110 allows the musician 100 to change between tactile members 106 as needed.

FIGS. 3A and 3B illustrate the tactile member 106 of the preferred embodiment in greater detail. FIG. 3A shows the tactile member 106 in a non-depressed state and FIG. 3B shows the tactile member 106 is a depressed state. As shown, the tactile member 106 has a square base 120 that is preferably 1/4" by 1/4" and a rounded upper surface that is formed from a hemisphere 122 positioned on the square base 120 that has a radius of approximately 1/4". The tactile member 106 also has a central passage 124 that extends its full length that is roughly circular in cross section and has a diameter of 1/8". The tactile member 106 is made out of a substantially air-tight material so that depression of any one portion of the tactile member 106 results in a proportionate change in pressure inside the central passage 124 of the tactile member 106.

In the preferred embodiment, the tactile member 106 is made out of neoprene rubber that has been coated on both the outside surface and the inside surface of the central passage 124 with urethane to prevent leakage of air through the neoprene material. Neoprene material of the above-dimensions is pref...

METHOD AND APPARATUS FOR PLAYING IN SYNCHRONISM WITH A DIGITAL AUDIO FILE AN AUTOMATED MUSICAL INSTRUMENT
2010-03-04 00:00:00
In the present invention, the controller, through use of a digital audio data player incorporated into the controller, acts as both the MIDI Sequencer and the digital audio playback device, so the controller has inherent and immediate knowledge of what digital audio track or selection is being played and what that track's time progress is. Typically, these digital audio data files will contain musical performances and information identifying the musical selection such as artists, album, song length, and title. The object is to drive the automated musical instrument synchronously along with the musical selection or song of the digital audio file.

[0029] The pre-authored music sequences are synchronized to the digital audio stream of the digital audio data per track or per selection. This means that a particular track or musical selection is extracted from the digital audio medium by the authoring system. Once this is done, it is played by the authoring system which is simultaneously capturing a live piano performance along with it and converting that performance to a music sequence, typically in MIDI format. The time stamps for the music sequence use the extracted digital audio data or stream as its source of time reference rather than some other system time. Hence, the resulting music sequence is synchronized to the digital audio track on any playback system as long as the playback system uses the digital audio data stream as its time reference.

[0030] Once the music sequence is authored or pre-authored as the process is alternatively named, it is associated with the musical selection in some way. Since the Sync-Along device or controller is always the renderer of the digital audio data, it has specific knowledge of the selected track or selection that is being played, such as the title, artists, song length and Volume ID, and is always aware of exactly what track or selection is being played. As such, the specific information such as title and artist are stored as either Meta Events within the MIDI Sequence, or as part of the filename of the MIDI Sequence, allowing the controller to recognize what music sequence matches the song or selection being played. One skilled in the art will recognize other identifying information can be used to match the MIDI file to the musical selection.

[0031] Therefore, when a controller is instructed by the user to playback a particular selection, the system loads the requested music sequence along with its identifying information and checks to make sure that that particular song's digital audio data file is loaded for playback.

[0032] Playback of digital audio data is implemented by the controller by reading the digital audio data, directly off of the storage media such as a CD or SD card and sending that data to its DAC Subsystem for rendering to an analog signal. If the file is compressed, such as an MP3 file, the file is uncompressed prior to or during playback. Generally, the file is decompressed as the data is read and the resulting linear or PCM data is buffered locally for playback. The DAC Subsystem itself is regulated by the audio rate of the DAC, which will nominally run at 44.1 kHz--or preferably the audio sample rate ...

Electronic music system and stringed instrument input device therefor
2010-03-02 00:00:00
instrument and associated electronic circuitry, for sequentially providing voltage signals, selected from a set of discretely different voltage levels each analogously related to a musical tone, for driving the tone generator. Each string-fret pair of the stringed instrument is assigned a given musical tone, preferably in accordance with normal tuning of the instrument, and means are provided for producing a corresponding voltage when a string-fret pair is closed by pressing the string against the fret. When two or more string-fret pairs are simultaneously closed, the output voltage corresponding to the highest frequency musical tone associated with the closed string-fret pairs is produced. In particular, different electrical voltages are applied to the instrument frets so as to apply such voltages to the strings when the strings are pressed into contact with the frets. A multiplexing system repetitively samples the string voltages, adds to each string voltage an offset voltage compensating for the musical intervals between the open strings, and processes the highest summed voltage for output to the tone generator.ClaimsWe claim:

1. An electronic music system comprising a voltage controlled tone generator, a stringed instrument having at least one string and a plurality of frets spaced from one another along thelength of said string with each string-fret pair representing an assigned musical tone, and means responsive to said string being pressed into contact with any one of said frets for producing and supplying to said voltage controlled tone generator, asthe driving input signal for said tone generator, a voltage signal having a voltage 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...

Generation of noise-like tones in an electronic musical instrument
2010-02-27 00:00:00
this transfer is made. Thus the words stored in the Note shift register 35 are continuously being modified in a randomly selected manner before beingtransferred to the digital-to-analog converter 47. The resulting audio tone, while still retaining the fundamental frequency as fixed by the Note clock 37, varies in upper harmonic content in a random manner which is heard as a noise superimposed on thebasic tone. It should be noted that the master data list in the main register 34 may initially define any conventional waveshape, such as a simple sine wave, a sawtooth wave, or a complex tone. FIG. 2 shows a plot of the waveform, assuming a sinusoidalwaveform stored in the main register 34 is modified by the right shift of words selected on a random basis. The noise-like signal is easily recognized in the plotted waveshapes. The spectrum of each cycle of the waveshape is shown. In each case thefundamental is retained as the strongest component, establishing the musical pitch, while the higher order components change in relative power to provide the desired noise-like effect.

Referring to the block diagram of FIG. 3, an alternative embodiment is disclosed which is substantially the same as that shown in FIG. 1, except that a 2's complement circuit 203 is substituted for the Right Shift circuit of FIG. 1. Thus wordsbeing transferred from the main register 34 to the Note shift register 35 are modified to the 2's complement of the word at random times as determined by the random binary signal generator 202. It should be noted that the frequency at which the randombinary signal generator 201 operates need not be the same as the frequency of the Note clock 37, although it may be synchronized with the Note clock 37 if desired.

FIG. 4 shows twenty successive data transfers and their associated spectra for the circuit of FIG. 3. The master data list in the main register 34 corresponds to a simple sinusoid at the fundamental frequency. As can be seen from the waveformsof FIG. 4, the random 2's complement data transfer creates tones having a wide band noise-like spectra.

Referring to FIG. 5, there is shown yet another alternative embodiment in which the random binary signal generator 201 is used to select either of two words from the...