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Multi-feature speech/music discrimination system
2010-03-29 00:00:00
situations where the data can be readily divided into two distinct clusters, which can be separated by such a simple decision boundary. However, there may be situations in which the dispersion of the data for the different classes is somewhat homogenous within the feature space. In such a case, the Gaussian decision boundary is not as reliable. Accordingly, it is another object of the present invention to provide a speech/music discriminator having a classifier that permits arbitrarily complex decision boundaries to be employed, and thereby increase the accuracy of the discrimination.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a set of features is provided which can be selectively employed to distinguish speech content from music in an audio signal. In particular, eight different features of a digital audio signal can be measured to analyze the signal. In addition, higher level information is obtained by calculating the variance of some of these features within a predefined time window. More particularly, certain features differ in value between voiced and unvoiced speech. If both types of speech are captured within the time window, the variance will be relatively high. In contrast, music is likely to be constant within the time window, and therefore will have a lower variance value. The differences in the variance values can therefore be employed to distinguish speech sounds from music. By combining data from some of the base features with data from other features, such as the variance features, significant increases in the discrimination accuracy are obtained.

In another aspect of the invention, a "nearest-neighbor" type of classifier is used to distinguish speech data samples from music data samples. Unlike the Gaussian classifier, the nearest-neighbor classifier estimates local probability densities within every area of the feature space. As a result, arbitrarily complex decision boundaries can be generated. In different embodiments of the invention, different types of nearest-neighbor classifiers are employed. In the simplest approach, the nearest data point in the feature space to a sample data point is identified, and the sample is labeled as being of the same class as the identified nearest neighbor. In a second embodiment, a number of data points within the feature space that are nearest to the sample data point are determined, and the new sample point is classified by a voting technique among the nearest points in the feature space. In a preferred embodiment of the invention, the number of nearest data points in the feature space that are employed for such a decision is small, but greater than unity.

In a third embodiment, a K-d tree spatial partitioning technique is employed. In this embodiment, a K-d tree is constructed by recursively partitioning the feature space, beginning with the dimension along which features vary the most. With this approach, the decision boundary between classes can become arbitrarily complex, in dependence upon the size of the set of features that are used to provide input data. Once the feature space is divided into sufficiently small regions, a voting technique is employed among the data points within the region, to assign it to a particular class. Thereafter, when a new sample data point is generated, it is labeled according to the region within which it falls in the feature space.

The foregoing principles of the invention, as well as the advantages offered thereby, are explained in greater detail hereinafter with reference to various examples illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a general block diagram of a speech/music discriminator embodying the present invention;

FIG. 2 is an illustration of an audio signal that has been divided into frames;

FIGS. 3a and 3b are histograms of the spectral centroid for speech and music signals, respectively;

FIGS. 4a and 4b are histograms of the spectral flux for speech and music signals, respectively;

FIGS. 5a and 5b are histograms of the zero-crossing rate for speech and music signals, respectively;

FIGS. 6a and 6b are histograms of the spectral roll-off for speech and music signals, respectively;

FIGS. 7a and 7b are histograms of the cepstral resynthesis residual magnitude for speech and music signals, respectively;

FIG. 7c is a graph showing the power spectra for voiced speech and a smoothed version of the speech signal;

FIGS. 8a and 8b are graphs depicting variances between speech and music signals, in general;

FIGS. 9a and 9b are histograms of the variation in spectral flux for speech and music signals, respectively;

FIGS. 10a and 10b are histograms of the proportion of low energy frame...

Musical apparatus using multiple light beams to control musical tone signals
2010-03-25 00:00:00
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 reflected light beams are detected, the device controls the musical tone signal based only on one of the reflected light beams, the one that is detected first. U.S. Pat. No....

Low profile keyboard device and system for recording and scoring music
2010-03-23 00:00:00
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 againrequires the elaborate installation of sensitive electronics to the underside of a keyboard, with the accompanying disadvantages of being costly and requiring skilled persons to render the invention useful. U.S. Pat. No. 3,905,267, entitled"ELECTRONIC PLAYER PIANO WITH RECORD AND PLAYBACK FEATURE," to Vincent, teaches an electronic data storage system including a magnetic type recorder/replayer for recording spontaneous musical presentations for replay through a similar instrument. Tocapture the musical data, the invention also requires extensive and expensive modifications to the underside of each key in the instrument. See also U.S. Pat. No. 4,023,456, entitled "MUSIC ENCODING AND DECODING APPARATUS," to Groeschel, for yetanother example of how electronic switching to monitor keyboard action requires bulky circuitry and modification of the keyboard from within the instrument.

The sequencer is a viable alternative method of recording music which has been developed in the prior art, although early in its development, the sequencer was a massive network of electronics, often covering walls in a recording studio. Musicians are able to record and immediately play back music with the use of sequencers. A sequencer, in its simplest form, consists of a series of adjustable voltage memories stepped by a clock pulse. The typical analog sequencer uses potentiometersand variable resistors, each including a manually operable dial for establishing a certain DC voltage In order to load the sequenc...

Automatic performance apparatus of an electronic musical instrument
2010-03-15 00:00:00
keys, each of which provides key switches thereunder to detect the OPEN or CLOSED state thereof. The keyboard 1 is divided into three key-areas, KB1 to KB3, in which the output signal of each key in the key-area KB1 is supplied to a manual performance musical tone generating circuit 2 and a chord data generating circuit 3. The output signal of each key in the key-area KB2 is supplied to manual performance musical tone generating circuit 2, and the output signal of each key in the key-area KB3 is supplied to manual performance musical tone generating circuit 2 and note length data generating circuit 4 respectively.

The manual performance musical tone generating circuit generates a musical tone signal corresponding to the depressed key on keyboard 1 and outputs this musical ton signal to an amplifier 5. The chord data generating circuit detects the depressed key in key-area KB1 to generate its chord data in accordance with the detected key data, in which chord data indicates a chord of an accompaniment tone.

In the present embodiment, many types of chords such as C major or A minor are designated by the key operation of key-area KB1. For example, depressing keys C, E, and G of key-area KB1 designates C major. The chord data generating circuit 3 receives a signal based on the key which is depressed in key-area KB1. According to this received signal, the chord data generating circuit 3 generates chord data which includes basic tone data CCD indicated by the basic tone of the chord (C, D, E, or the like) and type data TPD indicated by type of the chord (major minor, or the like). In accordance with the generated chord data, an automatic accompaniment tone is generated as described later. The note length data generating circuit 4 generates note length data FTD corresponding to the depressed key in key-area KB3. Herein, the note length data of the accompaniment chord is indicated by the key operation of key-area KB3. The note length data generating circuit 4 then outputs note length data FTD to the next circuit in accordance with the detected key data of key-area KB3.

A tone color switch 6 is used for setting the tone color of the accompaniment tone; an effect switch 7 for setting an effect of the accompaniment tone; a melody-ON switch 8 for storing a starting signal of a melody tone in the automatic performance; a melody-OFF switch 9 for storing a stopping signal of the melody tone in the automatic performance; a multi-stage tone volume switch 10 is used for controlling the volume of the accompaniment tone; and an end switch 11 is used to indicate the completion of the accompaniment tone.

Numeral 12 designates a record switch which is CLOSED when writing data to chord sequence memory CM. A play switch 13 CLOSES when reading data stored in chord sequence memory CM to automatically perform the accompaniment tone. A start-stop switch 14 manually turns the melody tone on and off during the automatic performance.

A code converter circuit 16 generates the registered data corresponding to one of the operated switches 6 to 11. The registered data includes registered type data RGS and registered content data RGD, in which registered type data RGS indicates a type (tone color switch, effect switch, etc.) of the operated switch, while registered content data RGD indicates a switch number, a...

Wavetable-modification instrument and method for generating musical sound
2010-03-12 00:00:00
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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 new address for each value of yn stored.

13. The instrument of claim 12 wherein means for sequentially changing said Write Pointer address includes means for decrementing said Write Pointer address.

14. The instrument of claim 7 including means for storing said Write Pointer address, means for storing said Read Pointer address offset by an integer proportioned to N from said Write Pointer address, and means for sequentially changing saidWrite Pointer address and said Read Pointer address whereby the offset between said Write Pointer address ...

Method for encoding music printing information in a MIDI message
2010-03-10 00:00:00
may contain any number of data bytes and can be terminated either by an end of exclusive or any other status byte, with the exception of Real-Time messages. An end of exclusive should always be sent at the end of a system exclusive message. System exclusive messages always include a manufacturer's identification code. If a receiver does not recognize the identification code it will ignore the following dam.

As those skilled in the art will appreciate upon reference to the foregoing, musical compositions may be encoded utilizing the MIDI standard and stored and/or transmitted utilizing substantially less than data than would otherwise be required. The MIDI standard permits the transmittal of a serial listing of program status messages and channel messages, such as "note on" and "note off" and as a consequence require substantially less digital data to encode than the straightforward digitization of an analog musical signal. Using the MIDI system provides additional advantages including the ability to transmit the MIDI signals to a variety of MIDI-compatible devices to allow simultaneous translation of a single signal for multiple purposes and also to allow mixing signals to a variety of devices on a single signalling connection.

Extensions to MIDI

The MIDI standard was originally designed for communication between electronic instruments. About the time it was being developed, however, it was also becoming clear to many people that not only could one musical instrument be used to control another, but musical instruments themselves could be controlled by computer. Put another way, a sequence of electronic (MIDI) commands that might be generated (in a performance) on a musical keyboard could also be generated by computer. The receiving instrument has no way to know what the origin of the commands is (computer vs. live performance). In a similar manner, the "sending" instrument knows nothing about the nature of the "receiving" instrument under the MIDI standard. It is therefore possible for the receiving instrument to be a computer, which is actually recording (receiving and storing) the MIDI signals from the sender. In this way, a musical performance (defined as a series of physical gestures on an electronic keyboard), can be recorded (received and stored) on a computer and later played back on (sent to) the same keyboard or some other sound generating device which "understands" MIDI commands.

With the advent of "MIDI" recordings and simulated recordings compiled by software, the need arose to find a way to pass this data from one computer to another. Also there were several descriptive aspects of the music not...

Control system for a musical instrument
2010-03-09 00:00:00
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7. The control system of claim 6, wherein said controller, when in said operation mode, produces an audio signal having a volume audio characteristic which is at least said initial starting volume and wherein said controller increases said volume audio characteristic from said initial starting volume in proportion to said first signal generated by said musician exerting pressure on said tactile member.

8. The control system of claim 7, wherein said controller, when in said operation mode, sustains the volume audio characteristic of said audio signal produced by said musical instrument at a first level, which is proportionate to the greatest amount of pressure exerted on said tactile member by said musician, until said musician exerts a greater amount of pressure on said tactile member.

9. The control system of claim 1, wherein said controller, when in said program mode, can be programmed by said musician to set a plurality of initial starting frequencies and a plurality of initial starting amplitudes of a tremolo audio characteristic of said audio signal produced by said musical instrument.

10. The control system of claim 9, wherein said controller, when in said operation mode, produces an audio signal having a tremolo audio characteristic having one of said plurality of initial starting frequencies and having one of said plurality of initial starting amplitudes.

11. The control system of claim 10, wherein said controller, when in said operation mode, increases the frequency of said tremolo audio characteristic in response to said musician exerting pressure on said tactile member.

12. The control system of claim 11, wherein said controller is configured, in said operation mode, so that said musician can switch between said plurality of starting frequencies and said plurality of starting amplitudes of said tremolo audio characteristic by manipulating said plurality of user inputs.Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a system for controlling the output-of a musical instrument and, in particular, concerns a system which includes a pressure sensitive control device which is mounted on a musical instrument to allow the player of the instrument to alter various characteristics of the audio output signal of the musical instrument.

2. Description of the Related Art

Electric guitars are extremely popular musical instruments as they can produce a wide range of different sounds when they are used in conjunction with an amplifier. The musician can produce sound signals having a wide range of volume with an electric guitar and the musician can also produce a sound signal from the electric guitar that has a particular sound quality. For example, using the amplifier, the musician can produce a sound signal having a characteristic which varies in volume over time. This characteristic is generally referred to as tremolo. Other types of sound signals that can be produced using an electric guitar include reverberation, vibrato and the like.

The sound signals produced by the guitar are generally adjusted by the musician either changing the settings of dials on the guitar, or by changing settings of dials on an amplifier. Foot pedals are also often used to change the characteristics of the audio signals produced by an electric guitar. It can be appreciated, however, that these devices for changing the characteristics of the sound signals have several disadvantages for the musician.

Specifically, if the musician has to remove his hands from the strings of the guitar to adjust a dial, he cannot continue playing the instrument during that interval. This causes disruptions in the melody that the musician is playing. This problem is somewhat solved by foot pedals which are linked to the amplifier and effectuate changes in characteristics of the audio signal. However, the foot pedals are generally fixedly positioned in one place which requires that the musician also remain in the same place. In many musical performances, the musicians prefer to move around the stage, and their ability to do so is hampered when they have to remain in the proximity of the foot pedals to effectuate changes in the characteristics of the audio signals that they are producing.

One possible solution to this problem has been proposed in U.S. Pat. No. 3,443,018 to Krebs. The Krebs patent discloses an electric guitar wherein compressive rubber resistance elements are built into the neck of the guitar at specific locations. These elements can be used by the musician to change various characteristics of the sound signals, e.g., the volume, by depressing the elements while playing the guitar. However, the guitar in the Krebs patent still suffers from several difficulties.

First, Krebs discloses a guitar wherein the compressive rubber elements are embedded in the neck of the guitar. This requires that the guitar be specially made to facilitate these rubber elements or that the neck of existing guitars be drilled and hollowed to facilitate the rubber elements. Further, the rubber elements are generally small in size and made of a solid piece of rubber. While a solid piece of rubber can be depressed by an individual, the tactile feel of a solid piece of rubber is generally very poor.

In particular, a musician who is depressing one of the elements to change a characteristic of the audio signal in the Krebs guitar will generally not be able to predict ahead of time the exact change of a characteristic of the audio signal. The musician will generally have to wait until the audio signal is produced, and then exert more or less pressure on the element to adjust the signal to have the desired characteristic. Hence, the desired audio signal may not be produced at the desired time or the characteristic may initially be not what the musician intended.

A further difficultly with the Krebs device is that some desired changes in characteristics of audio signals still require the musician to remove his hands from the guitar to effectuate the desired change. For example, if the musician wishes to change the tremolo, e.g., change the frequenc...

Musical apparatus detecting maximum values and/or peak values of reflected light beams to control musical functions
2010-03-08 00:00:00
information based on a characteristic of radiation received from each of the at least two light paths;

receiving performance data from a performance signal source;

generating an audio signal based on the performance data; and

controlling a characteristic of the audio signal based on the generated information.

10. A method as recited in claim 9, wherein receiving radiation reflected from an object comprises receiving light reflected from an object.

11. The method recited in claimed 9, wherein receiving performance data from a performance signal source comprises receiving performance data from a digital music signal source.

12. The method recited in claim 9, wherein receiving performance data from a performance signal source comprises receiving performance data from a Musical Instrument Digital Interface ("MIDI") signal.

13. The method recited in claim 9, wherein generating information based on a characteristic of radiation received from each of the at least two paths comprises:

generating at least two detection values, each of which is based on a characteristic of radiation received from each of the at least two paths;

detecting a maximum value of each of the at least two detection values; and

controlling a characteristic of the audio signal based on a correlation between the maximum values of the at least two detection values.

14. The method recited in claim 9, wherein the audio signal is a tone signal.

15. The method recited in claim 9, wherein generating information based on a characteristic of the radiation received from each of the at least two paths comprises generating information based on a quantity of radiation received from each of the at least two paths.

16. The method recited in claim 13, wherein generating at least two detection values, each of which is based on a characteristic of radiation received from each of the at least two paths comprises generating at least two detection values, each of which is based on a quantity of light received from each of the at least two light paths.

17. A method of controlling and outputting music based on the motion of an object within a specified space, the method comprising:

receiving radiation reflected from an object within the specified space,

controlling a characteristic of the received radiation by moving the object within the specified space;

generating a detection value based on the characteristic of the received radiation;

receiving performance data from a performance signal source;

generating an audio signal based on the performance data,

outputting the audio signal; and

controlling the audio signal based on the detection value.

18. A method as recited in claim 17, further comprising emitting radiation into the specified space.

19. A method as recited in claim 18, wherein emitting radiation comprises emitting light and wherein receiving radiation comprises receiving reflected light.

20. A method as recited in claim 17, wherein receiving radiation comprises receiving light reflected from the object within the specified space.

21. A method as recited in claim 17, wherein receiving radiation comprises receiving light reflected along at least two paths from the object and wherein generating a detection value comprises generating a value dependent upon a characteristic of light received along the at least two paths.

22. The method recited in claim 17, wherein the audio signal is a tone sign...