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Multi-feature speech/music discrimination system
2010-03-29 00:00:00
AbstractA speech/music discriminator employs data from multiple features of an audio signal as input to a classifier. Some of the feature data is determined from individual frames of the audio signal, and other input data is based upon variations of a feature over several frames, to distinguish the changes in voiced and unvoiced components of speech from the more constant characteristics of music. Several different types of classifiers for labeling test points on the basis of the feature data are disclosed. A preferred set of classifiers is based upon variations of a nearest-neighbor approach, including a K-d tree spatial partitioning technique.Claims

What is claimed is:

1. A method for discriminating between speech and music content in an audio signal, comprising the steps of:

selecting a set of audio signal samples;

measuring values for a plurality of features in each sample 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 each data point as relating to speech or music;

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

classifying the test sample in accordance with the determined label.

2. The method of claim 1 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.

3. 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 contai...

Musical apparatus using multiple light beams to control musical tone signals
2010-03-25 00:00:00
tones by detecting motion of an object in a space adjacent to the musical apparatus. More specifically, the musical apparatus may comprise a musical tone signal generator which generates a musical tone signal, at least one light source which radiates light beams into a space adjacent to the musical apparatus, at least one light detector which detects at least two light beams reflected from an object in the space and generates a detection value for each of said at least two light beams, a computing element which receives the detection values and generates a synthesized value; and a controller which controls parameters of musical tones based on the synthesized value. For example, the synthesized value may be the sum of the detection values, the difference between the detection values, the ratio between the detection values, or some other relationship between the detection values.Claims

What is claimed is:

1. An electronic sound generating system which responds to the motion of an object in a space exterior to the electronic musical system in order to control a sound function, the system comprising:

at least one radiation source that emits radiation into a space outside the electronic sound generating system where the emitted radiation hits an object in the space;

at least one detector that detects radiation reflected along at least two paths from the object in the space outside the electronic sound generating system to detect motions of the object;

a controller for generating a control signal for controlling the sound function dependent on the motions of the object; and

a tone generator for generating a sound that is at least partially dependent upon the sound function.

2. The system of claim 1, wherein the radiation source that emits radiation comprises a light source that emits at least one light beam and wherein the detector that detects radiation comprises a light detector that detects light reflected along at least two paths from the object.

3. The system of claim 1, wherein the sound function is an audio signal.

4. The system of claim 1, Wherein the sound function is a tone signal.

5. The system of claim 1, wherein the sound function is an electronic audio control signal.

6. The system of claim 5, wherein the electronic audio control signal comprises a MIDI signal.

7. An electronic audio control system which responds to the motion of an object in a space exterior to the electronic musical system in order to control a sound function, the system comprising:

at least one radiation source that emits radiation into a space outside the electronic musical system where the emitted radiation hits an object moving in the space;

at least one detector that detects radiation reflected from the object in the space outside die electronic audio control system and produces at least two detection values therefrom, the detection values being dependent upon the motion of the object; and

a controller for generating a control signal for controlling the sound function dependent on the motions of the object.

8. The system of claim 7, wherein the radiation source that emits radiation comprises a light source that emits at least one light beam and wherein the detector that detects radiation comprises a light detector that detects light reflected along at least one path from the object.

9. The system of claim 7, wherein the sound function is an audio signal.

10. The system of claim 7, wherein the sound function is a tone signal.

11. The system of claim 7, wherein the sound function is an electronic audio control signal.

12. The system of claim 11, wherein the electronic audio control signal comprises a MIDI signal.Description

FIELD OF THE INVENTION

The field of the invention is electronic musical apparatuses such as electronic musical instruments, music-related sound generation devices, music-related sound modification devices, and their controllers, including, for example, synthesizers, keyboards, drum machines, effects processors, effects pedals, sequencers and sound modules. More specifically, the electronic musical apparatus embodying the invention is controlled by detecting the location and/or movement of an object (e.g., a hand) within a space by using a plurality of light beams, including infrared light beams.

BACKGROUND OF THE INVENTION

An electronic musical apparatus which detects reflected light to control the musical tone signal is known. Such a device was disclosed in Japanese Laid-Open Utility Model Application Publication Number SHO 58-195296.

Japanese Laid-Open Utility Model Application Publication Number SHO 58-195296 discloses attaching a light quantity detection apparatus in order to detect and sense the amount of ambient light outside an electronic musical apparatus. It reacts to the amount of light that has been sensed by the light quantity detection apparatus and controls parameters that are related to the musical tone (hereinafter, simply referred to as "parameters") such as the musical interval, timbre and volume.

However, in the device disclosed in Japanese Laid-Open Utility Model Application Publication Number SHO 58-195296, the amount of light is detected by a single light quantity detection apparatus, and there is no disclosure in Japanese Laid-Open Utility Model Application Publication Number SHO 58-195296 of the detection of a plurality of light quantities.

In addition, U.S. Pat. No. 5,045,687 discloses that a space is irradiated with light such as infrared light, mutually different sound pitches are assigned in advance to the multiple number of light beams reflected from the specified objects in the space, said multiple number of reflected light beams are detected and musical tone signals are produced that possess pitches which conform to the reflected light beams that have been detected.

However, in the system disclosed in U.S. Pat. No. 5,045,687, if a plurality of reflecte...

Thumbrest ring adapter for musical instrument
2010-03-24 00:00:00
to a thumbrest of a woodwind musical instrument, such as an oboe, clarinet, English horn or straight saxophone, to provide an attachment ring in those instances when the thumbrest of the instrument does not include a permanent attachment ring. The ring adapter assembly allows a support device to be attached to the musical instrument to relieve the weight on the thumb and hand of a musician playing the instrument. One embodiment of the ring adapter assembly is used with fixed position thumbrests and is adapted to be seated on a top surface of the thumbrest so that an attachment ring within the assembly faces away from the musical instrument. A top portion of the assembly may be moved up and down by an adjustment screw and includes a spring wire which extends around the thumbrest to connect the assembly to the thumbrest. Upward adjustment of the top portion increases the tension on the wire and the downforce applied to the assembly to maintain the assembly seated on the thumbrest. Another embodiment of the ring adapter assembly fixes an attachment ring to an adjustable thumbrest. The position of the ring adapter assembly on the thumbrest is adjustable to compensate for adjustments of the thumbrest in relation to the musical instrument. An attachment component for a monopod strut device is also disclosed. The attachment component is releasably attachable to the ring adapter assembly to support the musical instrument.Claims

The invention claimed is:

1. A ring adapter assembly for a musical instrument having a thumbrest which includes a horizontal projection extending outward from the instrument toward a musician and under which a thumb of the musician is conventionally placed, said assembly comprising:

a body;

attachment apparatus for connecting the body to the thumbrest without interfering with placement and position of the musician's thumb under the horizontal projection; and

an eye fixed to the body at a position above the horizontal projection of the thumbrest.

2. A ring adapter assembly as defined in claim 1, wherein the position of the horizontal projection is fixed in relation to the musical instrument, and wherein the body further includes:

a base having a bottom surface seated upon a top surface of the horizontal projection.

3. A ring adapter assembly as defined in claim 2, wherein the body further comprises:

a resilient, compressible surface bonded to the bottom surface of the base and adapted to be seated on the horizontal projection.

4. A ring adapter assembly as defined in claim 1, wherein a vertical post is fixed to a top surface of the horizontal projection of the thumbrest and a receptacle is fixed to the musical instrument to receive the vertical post and adjustably fix the position of the horizontal projection in relation to the musical instrument, and wherein:

the body further comprises an elongated horizontal surface defining a vertical opening at one end to receive the vertical post of the thumbrest and allow the horizontal surface to move along the vertical post; and

the attachment apparatus includes movement limiting means to fix the location of the horizontal surface relative to the vertical post.

5. A ring adapter assembly as defined in claim 4, wherein:

the horizontal surface further defines a threaded horizontal opening; and

the movement limiting means comprises a set screw extending through the threaded horizontal opening to contact the vertical post.

6. A ring adapter assembly as defined in claim 4, wherein:

the body further comprises a vertical surface attached to an end of the horizontal surface opposite the vertical opening; and

the eye is fixed to the vertical surface.

7. A ring adapter assembly as defined in claim 6, wherein the vertical surface and the eye extend below the horizontal surface.

8. A ring adapter assembly as defined in claim 6, wherein the vertical surface and the eye extend above the horizontal surface.

9. A ring adapter assembly as defined in claim 6, wherein:

the horizontal surface is fixed to the vertical post at a location above the receptacle; and

the vertical surface and the eye extend below the horizontal surface.

10. A ring adapter assembly as defined in claim 6, wherein:

the horizontal surface is fixed to the vertical post at a location below the receptacle; and

the vertical surface and the eye extend...

Low profile keyboard device and system for recording and scoring music
2010-03-23 00:00:00
attaches to a keyboard instrument for purposes of recording live musical performances; and an efficient music microcomputing system in which the captured musical data is digitized and further analyzed to determine note and note expression information when a key has been played. In the modular keyboard device, key and key expression data is captured by means of reflective couplers mounted in the keyboard device, and the information is transmitted to the processing unit. Microcomputer instructions refine the data to a format suitable for serial transmission via a computer-compatible link for ultimate scoring and recording.ClaimsI claim:

1. A portable, modular apparatus for acquiring data representative of a live musical performance on a selected keyboard instrument, said apparatus being removable positionable atop aback portion of the keyboard of the instrument, said apparatus comprising:

a housing designed with slots to fit atop a predetermined span of black and white keys on the keyboard of the selected keyboard instrument, said housing being structured for disposition atop the back portion of the keyboard and to operativelycover the predetermined span of keys on the keyboard;

reflective coupler means disposed within said housing, said reflective coupler means comprising light emitting means disposed to impinge light onto each key on the keyboard covered by said predetermined span means for receiving said lightreflected by each of the keys in accordance with the amount the key is depressed, and means for providing an electrical analog output signal corresponding to the amount of reflected light received from the key, and

means operatively connected to said reflective coupler means for monitoring the electrical analog output signal from said electrical analog output signal providing means to acquire data representative of the live musical performance.

2. The apparatus of claim 1 wherein said electrical analog output signal monitoring means comprises means for enabling each said analog output signal providing means at preselected time intervals.

3. The apparatus of claim 2 wherein said electrical analog output signal monitoring means comprises means for enabling said electrical analog output signal providing means in a preselected sequence.

4. The apparatus of claim 3 wherein said monitoring means comprises means for clocking said electrical analog output signal providing means to acquire data representative of key strike and release velocity.

5. The apparatus of claim 4 wherein said electrical analog output signal clocking means comprises means for clocking said electrical analog output signal sufficiently fast to provide data accurately representative of key strike and releasevelocities.

6. The apparatus of claim 4 wherein said monitoring means comprises means for comparing consecutive 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

Keyboard electronic musical instrument with guitar emulation function
2010-03-20 00:00:00
is used to trigger arpeggiated chords which emulate a strumming guitar sound. Select keys are provided for selecting which notes are included in chords to be strummed. At least one triggering device is also provided for triggering chords. The triggering device is constructed to alternate between two trigger states. The triggering device may be a keyboard key, foot pedal, or other device. The instrument operates in such a fashion that two arpeggiated chords of alternating direction (ascending and descending) may be produced during, and at least partially as a result of, one triggering device cycle from one state to the other and back again.Claims

What is claimed is:

1. An emulator for producing a guitar style performance from a controller, said controller including a user-operated triggering device for triggering arpeggiated chords which a user may alternate between a first trigger state and a second trigger state, and at least twelve keyboard keys assigned to a note select function, each of which a user may alternate between a rest key state and a selected key state, comprising:

a digital data processing system which receives trigger state information from said triggering device and key state information from said note select keys, and which sends commands to a tone generating device wherein,

a first state change of said triggering device from said first trigger state to said second trigger state when at least two of said note select keys are in said selected key state causes said data processing system to command said tone generating device to initiate production of a plurality of tones corresponding to the selected note select keys in an ascending sequence; and,

a second state change of said triggering device from said second trigger state to said first trigger state following said first triggering device state change as said selected note select keys remain in said selected key state causes said data processing system to command said tone generating device to (a) terminate production of said plurality of tones and (b) re-initiate production of said plurality of tones in a descending sequence.

2. An emulator as in claim 1 wherein;

said triggering device is a keyboard key.

3. An emulator as in claim 2 wherein,

said triggering device key is reciprocative between a rest position and a depressed position; and

said first and second trigger states are said rest and depressed key positions, respectively.

4. An emulator as in claim 1 wherein;

said triggering device is a vertically reciprocating foot pedal.

5. An emulator as in claim 4 wherein,

said triggering device foot pedal is reciprocative between a rest position and a depressed position; and

said first and second trigger states are said rest and depressed pedal positions, respectively.

6. An emulator as in claim 1 wherein;

said triggering device is a foot position sensing device which senses horizontal position of at least a portion of one of said user's feet.

7. An emulator as in claim 1 wherein,

each of said note select keys is reciprocative between a rest position and a depressed position; and

said rest and selected key states are said rest and depressed positions, respectively.

8. An emulator as in claim 1 wherein;

production of all of said tones initiated as a result of said first trigger state change is terminated as a result of said second trigger state change before the tones are re-initiated as a result of said second state change.

9. An emulator as in claim 1 wherein;

each of said tones initiated as a result of said first trigger state change is terminated as a result of said second trigger state change immediately prior to re-initiation; whereby,

as a result of said second state change, the highest pitched selected musical tone is muted and re-triggered, then the next lowest pitched selected musical tone is muted and re-triggered, followed by the next lowest tone.

10. An emulator as in claim 1 wherein;

state changes of said triggering device are affected through movement of a human appendage;

said data processing system receives information from said triggering device regarding the velocity with which said appendage effects trigger state changes;

said commands to initiate tone production include velocity data; and,

the velocity values corresponding with commands to initiate tone production for selected tones are a function of the velocity of the appendage movement which triggers the initiation of the selected tones.

11. An emulator as in claim 1 wherein;

said key state information includes information regarding aftertouch pressure applied to selected note select keys;

said commands to initiate tone production include velocity data; and,

the velocity values for selected tones are a function of aftertouch pressure applied to note select keys near the time of corresponding trigger state change.

12. An emulator as in claim 1 wherein;

said data processing system measures elapsed time between successive triggering device state changes; and,

elapse times between successive commands to initiate tone production for selected tones initiated as a result of a trigger state change are a function of the elapsed time between that trigger state change and the preceding trigger state change.

13. An emulator as in claim 1 wherein;

state changes of said triggering device are affected through movement of a human appendage;

said data processing system receives information from said triggering device regarding the velocity with which said appendage effects trigger state changes; and

elapse times between successive commands to initiate tone production for selected ton...

Device for cleaning wind musical instruments
2010-03-18 00:00:00
when contiguous to one another, an axially directed slit. A removable cleaning cloth is secured within the slit between the confronting walls of the half sections of the rod, when the confronting walls of the half sections are contiguous to one another. The cloth extends along the rod in the axial direction substantially the entire distance of the rod, when the walls of the half sections are contiguous to one another.Claims

What is claimed is:

1. A cleaning device for cleaning a tube of a wind musical instrument comprising:

(a) an elongated member having separable sections separable from one another along the axis of said elongated member, said separable sections confronting one another in the axial direction of said elongated member and defining therebetween a slit axially directed along the axis of said elongated member when said separable sections are disposed in contiguous relation;

(b) a cleaning cloth removably secured between said separable sections and disposed within said axially directed slit, said cleaning cloth having at least one flap extending out of said slit for cleaning the tube of the wind musical instrument, said flap being furled about said elongated member to prevent the elongated member from marring the tube of the wind musical instrument; and

(c) means for releasably securing said separable sections in contiguous relation,

(d) said slit extending substantially along the entire axial distance of said elongated member, and said cleaning cloth being disposed in and extending out of said slit substantially along the entire axial distance of said elongated member.

2. A cleaning device as claimed in claim 1 wherein said separable sections are formed with confronting walls between which said cloth is removably secured when said separable sections are disposed in contiguous relation, said device further comprising abrasive means adhering to said confronting walls to improve the securement between said separable sections and said cloth.Description

BACKGROUND OF THE INVENTION

The present invention relates in general to devices for cleaning musical instruments, and more particularly to a device for cleaning wind musical instruments.

The playing of wind musical instruments causes moisture to collect on the inner wall of the tube of the wind instrument. The breath of the instrumentalists condenses on th...

Automatic performance apparatus of an electronic musical instrument
2010-03-15 00:00:00
AbstractThe present invention relates to an automatic performance apparatus of an electronic musical instrument for activating and deactivating an automatic performance for each musical part such as melody tone, accompaniment tone, or rhythm tone. The first performance data memory stores an instruction signal which instructs the second reading circuit to start and stop reading performance data stored in the second performance data memory, so that the reading of the performance data stored in the second performance data memory can automatically start and stop in accordance with the progressing of the reading based on the performance data stored in the first performance data memory. Both performance data stored in the first performance data memory and in the second performance data memory are read by respective reading circuits, so that it is possible to selectively start and stop reading the performance data stored in both the first performance data memory and the second performance data memory.ClaimsWe claim:

1. An automatic performance apparatus of an electronic musical instrument comprising:

first automatic performance means for performing music comprising:

first memory means for storing first performance information and instruction information; and

first reading means for reading said first performance information and said instruction information from said first memory means;

second automatic performance means for performing music comprising:

second memory means for storing second performance information; and

second reading means for reading said second performance information from said second memory means; and

control means for controlling said second automatic performance means in response to the readout of said instruction information.

2. An automatic performance apparatus according to claim 1, wherein said first memory means comprises a chord sequence memory for storing said first performance information including basic tone data.

3. An automatic performance apparatus of an electronic musical instrument comprising:

first automatic performance means having a first performance data memory for storing first performance data and first reading means for reading out performance data stored in said first performance data memory;

second automatic performance means having a second performance data memory for storing second performance data and second reading means for reading out performance data stored in said second performance data memory; and

selection means for selecting at least one of said first automatic performance means and said second automatic performance means in accordance with the state of stored instruction data, said selection means comprising a start-stop switch and said stored instruction data comprising registered content data included in said first performance data memory.

4. An automatic performance apparatus of an electronic musical instrument comprising:

first automatic performance means having a first performance data memory for storing first performance data and first reading means for reading out performance data stored in said first performance data ...

Wavetable-modification instrument and method for generating musical sound
2010-03-12 00:00:00
accessed to provide an output signal which determines the musical sound. The output signal from the wavetable is probabilistically modified and stored back into the wavetable as modified data. The modified data, after a delay, is accessed from the wavetable and thereby becomes a new output signal. This process is periodically repeated whereby each new output signal is stored (after possibly being modified) back into the wavetable to produce rich and natural musical sound.ClaimsWhat is claimed is:

1. 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 N, including initialvalue means for storing input data values into said wavetable unit with said input data values having amplitudes determined at least in part randomly, including a modifier unit for combining two or more delayed data values from said wavetable unit toform a modified data value, and including selection means for selecting the modified data value 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, means for selectingthe stored value as the output signal at a rate independent of the pitch of the musical sound to be produced,

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

2. The musical instrument of claim 1 wherein said selection means includes means for selecting said modified data value or a delayed data value stochastically based upon a predetermined probability, d.

3. The instrument of claim 2 wherein said modifier unit includes an arithmetic unit for summing said two or more delayed data values from said wavetable unit and for dividing the summed data value by a number greater than unity to form saidmodified data value.

4. The instrument of claim 3 wherein said number greater than unity is 2 whereby said two or more delayed data values from said wavetable unit are averaged.

5. The instrument of claim 2 wherein said value has an amplitude yn at a sample time n greater than or equal to 0 where yn is given as follows, ##EQU7## where yn-N is the data value output from the wavetable after delay of N andwhere 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 signal amplitude loaded for an initial number of samples M into the wavetable and where rn is arandom number between 0 and 1 generated at sample time n.

6. The instrument of claim 5 wherein said output signal, at sample time n, is the data value having the amplitude yn.

7. The instrument of claim 5 wherein said wavetable unit is a random access memory, wherein the data value, yn, is stored in said memory at a Write Pointer address and wherein the data value yn-N is stored in said memory at a ReadPointer address, and wherein said Write Pointer address and said Read Pointer address are offset by a number of addresses equal to the number, N.

8. The instrument of claim 7 wherein the data value yn-(N 1) is stored in said memory at a Read Pointer 1 address which is offset from said Read Pointer address by 1.

9. The instrument of claim 5 wherein the values of xn initially stored in said wavetable represent "white noise".

10. The instrument of claim 9 wherein said values of xn 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.

11. The instrument of claim 5 including control means for producing the values of yn for the output signal at a sampling frequency, fs, and wherein the fundamental frequency of the sound produced for a pitch number N is approximatelyequal to fs /(N d/2).

12. The instrument of claim 7 including means for storing said Write Pointer address, means for storing the pitch number, N, as an address offset, means for calculating said Read Pointer address by summing said Write Pointer address and N, andmeans for sequentially changing said Write Pointer address to a n...

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