Musical applications of microprocessors pdf download

Internet Archive's 25th Anniversary Logo. Search icon An illustration of a magnifying glass. User icon An illustration of a person's head and chest. Sign up Log in. Web icon An illustration of a computer application window Wayback Machine Texts icon An illustration of an open book. Books Video icon An illustration of two cells of a film strip. Video Audio icon An illustration of an audio speaker. Instead, the sound vibrations are crudely analyzed into sine wave components and the amplitudes of the components are sent to the brain [or recognition.

The phases of the harmonics with respect to the fundamental are o[ little importance in tOnes of moderate frequency and amplitude. As a result, phase can usually be ignored when synthesizing sound waveforms. For example, the tones of Fig. The amplitudes of the harmonics in Fig. Obviously, the waveshape is not really a very good indicatOr of the timbre of the resulting sound.

Since the harmonic amplitudes are a good indicator of timbre, a different kind of graph called a spectrum plot is useful.

Such a graph is shown in Fig. The horizontal axis is now frequency and the vertical axis is amplitude, usually either the peak half of peak-to-peak value or the rms value. Each harmonic is represented by a vertical line whose height depends on its amplitude. When evaluating timbre, particularly lower-frequency tOnes with a lot of harmonics, the human ear is not usually supersensitive about the exact amplitude of a particular harmonic.

In most cases, the trend in amplitudes of. B Square wave with fundamental shifted C Square wave with random shift of all harmonics. A single harmonic, even the fundamental, can often be eliminated without great effect on the timbre. Accordingly, it is often useful to note the spectral envelope of the harmonics, which is indicated by a dotted line. It is interesting to note that even if the fundamental component amplitude is forced to zero the ear is still able to determine the pitch of the tone.

There ace a number of theories that attempt to explain how this is accomplished. One maintains that the ear is somehow capable of picking out the repetition rate of the waveform, which is not destroyed by removing the.

Another suggests that all of the remaining component frequencies are ascertained, and the missing fundamental frequency is "computed" from them. Nonrepeating Wavefonns With the basics of definitely pitched sounds with repeating waveforms in hand, lee's examine more closely the last three waveforms in Fig.

As mentioned earlier waveform C does not repeat but does have a pitch sense in relation to other similar sounds. Its spectrum is shown in Fig. Note that the sine wave component frequencies are not integral multiples of some fundamental frequency. This is the main reason that the waveform does not repeat and that it does not have an absolute pitch. However, since a small number of component frequencies relatively far from each other are involved, the sound is pleasing to hear, and the waveform trace is not unduly complex.

Actually, the statement about the waveform never repeating needs to be qualified a bit. If all of the frequencies are rational numbers it will repeat eventually.

If one of the frequencies is irrational, such as 7T kHz, however, the waveshape will indeed never repeat. At the moment, the presence or 1. Unpitched sounds and most semipitched sounds are like the waveforms of Fig. Time waveforms of such sounds give almost no clues about how they will sound. A spectrum plOt, however, will reveal quite a bit.

The first obvious feature is that there is a very large number of lines representing component sine waves. With such a large number, the spectral envelope takes on added significance.

In fact, most sounds of this type literally have an infinite number of component frequencies so the envelope is all that can be really plotted. The spectrum in Fig. It is nothing more than a straight line! Such a sound is called white noise because it has an even mixture of all audible frequencies.

This is analogous to white light, which is an evenmixture of all visible light frequencies. Any departure from a straight spectral plot can be called coloring the sound, analogous to coloring light by making one group of frequencies stronger than others. Pure white noise sounds like rushing air or distant surf. If the lower 1. If the high frequencies predominate, a hiss is produced. The middle frequencies can also be emphasized as in Fig. If a wide range of middle frequencies is emphasized, the sound is only altered slightly.

However, if a sufficiently narrow range is strengthened, a vague sense of pitch is produced. The apparent frequency of such a sound is normally near the center of the group of emphasized frequencies.

The narrower the range of frequencies that are emphasized, the more definite the pitch sensation. If the range is very narrow, such as a few hertz, a clearly pitched but wavering tone is heard. If the waveform of such a tone is examined over only a few cycles, it may even appear to be a pure, repeating, sine wave!

Multiple groups of emphasized frequencies are also possible with a clearly different audible effect. In fact, any spectrum envelope shape is possible. Parameter Variation In review, then, all steady sounds can be described by three fundamental parameters: frequency if the waveform repeats, overall amplitude, and relative harmonic amplitudes or spectrum shape.

The audible equivalents of these parameters are pitch, loudness, and timbre, respectively, with perhaps a limited degree of interaction among them.

What about unsteady sounds? All real sounds are unsteady to some extent with many useful musical sounds being particularly so. Basically a changing sound is a steady sound whose parameters change with time. Such action is frequently referred to as dynamic variation of sound parameters. Thus, changing sounds can be described by noting how the parameters vary with time.

Some terms that are often used in discussing parameter variation behavior are steady state and transition. If a parameter is changing only part of the time, then those times when it is not changing are called steady states.

Usually a steady state is not an absolute cessation of change but instead a period of relatively little change. The transitions are those periods when movement from one steady state to another takes place. An infinite variety of transition shapes are possible from a direct, linear change from one steady state to another to a variety of different curves.

Often it is the speed and form of the transitions that have the greatest influence on the overall audible impact of a sound. Frequency Variation Dynamic variation of frequency is perhaps the most fundamental.

A simple one-voice melody is really a series of relatively long steady states with essentially instantaneous transitions between them. If the frequency transitions become fairly long, the audible effect is that of a glide from note to note.

Often with conventional instruments, a small but deliberate wavering of frequency is added to the extended steady states. This wavering is called vibrato. If the frequency parameter is plotted as a function of time on a graph, then the vibrato shows up as a small amplitude waveform with the baseline being the current steady state.

This situation is termed frequency modulation because one waveform, the vibrato, is modulating the frequency of another waveform, the sound. We now have a whole new infinity of possible vibrato frequencies, amplitudes, and shapes. Gross alterations in the typical vibrato waveform can also have a gross effece on the resulting sound.

If the modulating wave amplitude is greatly increased to several percent or even tens of percent, the result can be a very boingy or spacey sound. If the modulating frequency is increased to tens or hundreds of hertz, the sound being modulated can be completely altered.

Clangorous sounds resembling long steel pipes being struck or breaking glass are easily synthesized simply by having one waveform frequency modulate another. This phenomenon will be studied in greater depth later. Amplitude Variation Changes in amplitude are also fundamental. Again taking a one-voice melody as an example, it is the amplitude changes that separate one note from another, particularly when two consecutive notes are of the same frequency.

Such an amplitude change delineating a note or other sound is frequently called an amplitude envelope or just envelope. The shape and duration of the amplitude envelope of a note has a profound effect on the overall perceived timbre of the note, often as important as the spectrum itself.

Figure shows a generalized amplitude envelope. Since they are so important, the various transitions and steady states have been given names. The initial steady state is, of course, zero or silence. The intermediate steady state is called the sustain, which forms the body of many notes. The transition. The duration of the attack is of primary importance, although its shape may also be important, particularly if the attack is long. The transition from the sustain back to zero is the decay.

Again, time is the major variable. Some notes, such as a piano note, have no real sustain and start to decay immediately after the attack. They may, however, have two different rates of decay, a slow initial one, which could be considered the sustain, even though it is decaying, and a faster final one.

Other envelope shapes are, of course, possible and quite useful in electronic music. As with frequency variation, an amplitude envelope may have a small wavering superimposed on the otherwise steady-state portions. Such amplitude wavering is called tremolo and, if small in amplitude, sounds much like vibrato to the untrained ear. Actually, the physical manipulation required to waver the tone of conventional instruments seldom results in pure vibrato or tremolo; usually both are present to some degree.

Large-amplitude tremolo gives rise to an unmistakable throbbing sound. Generalized amplitude modulation of one waveform by another is also possible, and in many cases the effects are similar to frequency modulation. This will also be examined more closely later.

Spectrum Variation Finally, dynamic changes in the spectrum of a tone are the most interesting and the most difficult to synthesize in general. The primary difference between spectrum variation and frequency or amplitude variation is that a spectrum shape is multidimensional and the other two parameters are single-dimensional.

Because of this multidimensional nature, standard electronic synthesis techniques for dynamic spectrum changes generally utilize schemes that attempt to cover a wide range of timbres by varying only one or two parameters of a simplified spectrum shape. One obvious way to control and vary the spectrum is to individually control the amplitudes of the individual harmonics making up the tone. This is a completely general technique applicable to any definitely pitched tone.

The problem with actually accomplishing this is twofold. The first is the myriad of parameters to controldozens of harmonic amplitudes for moderately pitched tones.

Involving a computer or microprocessor is the only reasonable approach to such a control task. The other problem is deciding how the harmonic amplitudes should vary to obtain the desired effect, if indeed even that is known. There are methods such as analyzing natural sounds, evaluating mathematical formulas, or choosing amplitude contours at random and subjectively evaluating the results that work well in many instances.

In any case, a computer would probably be involved in generating the data also. As mentioned previously, common synthesis techniques aim at reducing the dimensionality of the spectral variation problem. Consider for a. Disregarding the exact shape of the bell-shaped curve, it should be obvious that three parameters can adequately describe the spectrum.

First, there is the width and height of the peak on the curve, and finally the frequency at which the peak is highest. In a typical application, the width and height of the curve are related. Also, since only the relative height of one portion of the curve with respect to another is important, the absolute height parameter is usually eliminated. This leaves just the width and center frequency as variables. Note that for definitely pitched, periodic sound waveforms the spectrum curve being considered is really the envelope of the individual harmonic amplitudes.

It turns out that manipulation of these two variables is sufficient to create very interesting dynamic spectrum changes. In fact, if the width variable is set to a reasonable constant value such as Y3 octave at the 6-dB down with respect to the peak points, then varying just the center frequency is almost as interesting.

This in fact is the principle behind the "wah-wah" sound effect for guitars that became popular years ago. Other methods for changing or distorting the spectrum under the influence of a small number of parameters exist and will be covered in more detail later. Simultaneous Sounds The preceding should serve as a brief introduction to the fundamental parameters of a single, isolated sound.

Most interesting music, however, contains numerous simultaneous sounds. One common use for simultaneous sounds is chords and harmony. Another application is rhythm accompaniment. Sometimes quantities of sound are used simply as a kind of acoustical background for a simpler hut more prominent foreground. The physics and fundamental parameters of each component sound remain unaltered, however. The real frontier in synthesis, after adequate control of the basic.

Extensive use of microprocessors in synthesis will be the final stride toward reaching this goal. History of Electronic Sound Synthesis Sound and music synthesis by electronic means has a long and interesting history. Although only the most significant milestones can he briefly described here, the effort is certainly worthwhile, since the ongoing evolution of synthesis techniques and equipment is far from complete. Without exception, significant developments in sound synthesis closely followed significant developments in electronic and computer technology.

Often, how-. The Telehannonium One of the earliest serious musical instruments that produced sound by purely electrical means was conceived and built by Thaddius Cahill in The device was called the Teleharmonium, and the name fairly accurately described the principles involved. As with many synthesis developments, the profit motive was the major driving force. Cahill's basic concept was to generate music signals electrically and transmit them to subscriber's homes over telephone lines for a fee.

The signals would be reproduced by loudspeakers for "the continuous entertainment of all present. At the performer's end, the device resembled a conventional pipe organ console with two piano-like keyboards and numerous stops for controlling the timbre. Tone signals, however, were generated at kilowatt levels by specially constructed multipole, multiarmature electric generators located in the basement.

Each generator had eight outputs representing a particular note pitch at octave intervals for the 8-octave range. Such generators were reasonably straightforward to build but were large, heavy, and expensive. Although 12 were planned to cover all of the notes in an octave, only 8 were actually built. The high power levels produced were needed to serve the large number of subscribers expected and overcome transmission losses. In addition to the generators, special multiwinding "mixing transformers" were used to combine several tones together.

A limited amount of harmonic mixing was utilized to vary the timbre. This was possible without additional windings on the generators, since the first six harmonics of. The amplitude levels of the tones were controlled by means of inductors with movable cores to vary the inductance. In addition to the tonnage of iron, miles of wire were used to connect keyboard contacts to the other equipment.

Overall, the machinery that was built weighed over tons and required 30 railroad flatcars to move. Generally, the device worked well and was adequately accurate and stable. One problem that was eventually overcome was key click. Since the tones were being continuously generated and merely switched on and off with contacts, the attack of a note was instantaneous. If a key contact closed at a time when the signal being switched was near a peak, a sharp rising transient would be generated in the output line.

The solution to the problem was additional filter transformers to suppress the transients. The other problems were mostly economic. Since the planned 12 generators were not available, some of the notes were missing, resulting in a. Another difficulty was that the pressure of delivering continuous music to the subscribers already signed up severely limited the amount of machine time available for practice and further refinement. Listeners' reactions to Teleharmonium music were interesting.

The initial reaction was quite favorable and understandably so. No one had ever heard pure, perfectly tuned sine waves before and the sparkling clear unwavering quality of the sound was quite a novelty. Over long periods of time, however, the novelty was replaced by subtle irritation as the overly sweet nature of pure sine waves became apparent. The limited harmonic mixing technique that was later developed did little to remedy the situation, since six harmonics are too few for the lower-pitched tones and even fewer were provided for the higher-pitched ones due to generator limitations.

A related problem was the extremely poor loudspeakers available at the time. Bass response was totally absent and the many sharp resonances of the metal horns would frequently emphasize particular notes or harmonics many times over their nominal amplitude. For Cahill, the project was a financial disaster, its fate eventually sealed by radio broadcasting.

The basic concepts live on, however, in the Hammond electronic organs. The "tone wheels" used in these instruments are electric generators that perform exactly as Cahill's except that the power output is only a few micro watts rather than many kilowatts. The needed amplification is supplied by electronic amplifiers. Mixing, click suppression, and harmonic amplitude control are performed by resistive networks requiring only additional amplifier gain to overcome their losses.

The eighth harmonic, which is also on the equal-tempered scale, was added, skipping the seventh altogether. Still, the Hammond organ has a distinctive sound not found in any other type of electronic organ. Soundtrack Art Somewhat later, around after sound was added to motion pictures, some work was done with drawing sound waveforms directly onto film. Theoretically, this technique is infinitely powerful, since any conceivable sound within the frequency range of the film equipment could be drawn.

The difficulty was in figuring out exactly what to draw and how to draw it accurately enough to get the desired result. The magnitude of the problem can be appreciated by considering how a single, clear tone might be drawn. The clearness of a tone depends to a great degree on how accurately the waveform cycles repeat. Gradual variations from cycle to cycle are desirable, but imperfections in a single cycle add roughness to the tone. For even the simplest of tones, the waveform would.

More complex or simultaneous tones would be even more difficult. In spite of these problems, at least one interesting but short and simple piece was created in this way. Like the Teleharmonium, the concept of drawing waveforms directly is now fairly common.

Computers and sophisticated programs, however, do the tedious waveform calculation and combination tasks. The Tape Recorder Without question, the most significant development in electronics for music synthesis as well as music recording was the tape recorder. The Germans first developed the wire recorder during World War II, and it was subsequently refined to utilize iron-oxide-coated paper tape.

Plastic film bases were later developed, and now magnetic tape is the highest fidelity analog sound recording technique in common use. When on tape, sound becomes a physical object that can be cut, stretched, rearranged, molded, and easily re-recorded. A new breed of abstract composers did just that and the result, called "musique concrete," sounded like nothing that had ever been heard before.

In fact, before the popularization of synthesizer music, the public's conception of electronic ml:lsic was of this form, which they usually characterized as a seemingly random collection of outrageous sounds. The name musique concrete stems from the fact that most, if not all, of the sounds used were natural in origin, i. Popular source material included water drips, sneezes, and squeaky door hinges.

Typical manipulations included gross speeding or slowing of the recorded sound, dicing the tape and rearranging parts of the sound often with segments in reverse, overdubbing to create simultaneous copies of the sound, and other tricks. Occasionally, a small amount of electronic equipment was used to filter and modify the sound in various ways.

Regardless of the actual source material, the distortions were so severe that the final result was completely unrecognizable. Although usage of this sound material need not result in abstract compositions, it usually did. The primary difficulty was in achieving accurate enough control of the distortion processes to produce more conventional pitch and rhythmic sequences.

Unfortunately, musique concrete did very little to popularize electronic music techniques, although it undoubtedly gratified a small circle of composers and listeners. One example is the theremin , which was an electronic tone source whose frequency and amplitude could be independently conrrolled by hand-waving near two metal plates.

Others include a. In the early s, however, work began on a general purpose instrument, the first electronic sound synthesizer. The control mechanism was a roll of punched paper tape, much like a player-piano roll.

Thus, it was a programmed machine and as such allowed composers ample opportunity to carefully consider variations of sound parameters. The program tape itself consisted of 36 channels, which were divided into groups. Each group used a binary code to control the associated parameter. A typewriter-like keyboard was used to punch and edit the tapes. Complex music could be built up from the basic two tonr;s by use of a disk cutting lathe and disk player, which were mechanically synchronized to the program tape drive.

Previously recorded material could be played from one disk, combined with new material from the synthesizer, and re-recorded onto another disk. The RCA synthesizer filled a room, primarily because all of the electronic circuitry used vacuum tubes.

Financing of the project was justified because of the potential for low-cost musical accompaniment of radio and television programming and the possibility of producing hit records. Extensive use of the machine emphasized the concept that programmed control was going to be necessary to adequately manipulate all of the variables that electronic technology had given the means to control.

Direct Computer Synthesis The ultimate in programmed control was first developed in the middle s and has undergone constant refinement ever since. Large digital computers not only controlled the generation and arrangement of sounds, they generated the sounds themselves!

This was called direct computer synthesis of sound because there is essentially no intermediate device necessary to synthesize the sound. The only specialized electronic equipment beyond standard computer gear was a digital-to-analog converter DAC , a comparatively simple device.

Simply put, a DAC can accept a string of numbers from a computer and plot waveforms from them as an audio signal suitable for driving loudspeakers or recording. Such a system is ultimately flexible. Absolutely any sound within a restricted frequency range and that range can easily be greater than the range of hearing can be synthesized and controlled to the Nth degree. Any source of sound, be it natural, electronic, or imaginary, can be described by a mathematical model and a suitable computer program can be used to exercise the model and produce strings of numbers representing the resulting waveform.

Sounds may be as simple or as complex as desired, and natural sounds may be imitated with accuracy limited only by the completeness of the corresponding mathematical model. No limit exists as to the number of simultaneous sounds that may be generated either. Often in such a system, a discrete sound source may be just a set of numbers describing the parame. Usually this would take only a few words of computer -storage out of the tens or hundreds of thousands typically available.

Obviously, such an all-powerful technique must have some limitation or else it would have completely superseded all other techniques. That limitation is time. Although large computers perform calculations at tremendous rates of speed, so many must be performed that several minutes of computer time are necessary to compute only a few seconds of music waveforms. The more complex the sound, the longer the calculations. The net result was that considerable time elapsed between the specification of sound and its actual production.

Considerable usually meant at least half a day due to typical management practices in large computer centers. Obviously, then, composing for the direct computer synthesis medium demanded considerable knowledge of the relation between mathematical models, sound parameters, and the ultimate sensation of the listener.

It also required that the composer have a clear idea of what was to be accomplished. Without such foreknowledge and careful planning, the delays incurred by excessive experimentation would be unacceptable and the cost of computer time prohibitive. Nevertheless, many of the greatest electronic musical works were realized using this technique. Voltage-ControUed Synthesizers Perhaps the complete antithesis of direct computer synthesis started to emerge in the middle largely as the result of development of silicon transistors and other semiconductor devices.

The concept was modular music synthesizing systems utilizing voltage-control concepts as a common organizational thread throughout the system. The modules could be easily connected together in an infinite variety of configurations that could be changed in seconds by rerouting patch cords or pins on patch boards. The whole assemblage could be played by a keyboard or a number of other manual-input devices.

In general, a voltage-controlled synthesizer module consists of a black box with inputs and outputs that are electrical signals. Signals are conceptually divided into audio signals that represent sound and control voltages that represent parameters. An amplifier module, for example, would have an audio signal input, a control input, and an audio signal output. Varying the de voltage at the control input would change the gain of the amplifier. Thus, it could be considered that the amplifier module altered the amplitude parameter of the sound passing through in accordance to the voltage at the control input.

A filter module likewise altered the timbre of a sound passing. Although oscillator modules had no signal inputs, control inputs altered the frequency of the output waveform and sometimes the waveform itself. The real power of the voltage-control concept lies in the realization that the only difference between a signal voltage and a control voltage is in the typical rates of change. Properly designed modules could process control voltages as easily as signals and could also be cascaded for multiple operations on the same or different parameters.

Unlike direct computer synthesis, experimentation was encouraged due to the personal interaction and ease of use of the synthesizer. In addition, familiarity with the audible effect of different modules could be obtained in only a few hours of experimentation.

Improvisation was also practical and widely practiced. One limitation of voltage-controlled synthesizers until recently, however, was that they were essentially monophonic, i. The problem lies not in the voltage control technique but in the human interface devices such as keyboards and ultimately in the ability of the performer to handle all of the variables.

This limitation has classically been overcome by the use of overdubbing to combine one musical line at a time with a multitrack tape recorder. Perhaps the most significant event in the popular history of electronic music occurred when a recording created with voltage-controlled equipment by Walter Carlos called "Switched On Bach" was released in For the first time, the general public was exposed to electronic music that was "real music" with melody, rhythm, and harmony.

This shattered the old myth that electronic music was always abstract and disorienting and created quite a bit of interest among performers, listeners, and advertising agencies. Microprocessors Today the microprocessor is the hottest technical development of the decade. The basic power of a computer that once cost thousands of dollars is now available for only tens of dollars.

Electronic music technology has and certainly will continue to benefit from microprocessors. Ultimately, techniques with the generality of direct computer synthesis and the ease of interaction of voltage-controlled synthesis will become commonplace.

Microprocessors are ideally suited to automating and rendering programmable the standard voltage-controiled music synthesizer. A microprocessor can easily remember, catalog, and reproduce the numerous interconnection patterns and control sequences typically used. It can also generate its own control sequences based on mathematical models, inp';ts from other sources, or random chance, This entire application area of mi-. The faster and more sophisticated microprocessors are becoming powerful enough for direct synthesis techniques to be applied with performance approaching that of large machines of only a few years ago and price tags in the reach of the serious experimenter.

Furthermore, costs of the faster but simpler microprocessors are such that a multiprocessor system, with a microprocessor for each sound to be synthesized simultaneously, is in the realm of practicality. What was once an oscillator circuit with separate waveforming circuits may become instead a microprocessor with suitably simplified direct synthesis programming.

These are the application areas that are the subject of Section III. All the different methods for generating the sound material necessary for electronic music can be roughly categorized into two groups: those that generate entirely new sounds via some kind of synthesis process and those that merely modify existing sounds. This dichocomy is not very rigid, however, since many synthesis methods depend heavily on modification of ot"herwise simple synthetic sounds for their results, and many modification methods so severely distort the original sound that the result could easily be considered to be synthetic.

Nevertheless, the fundamental component techniques making up a methodology can be easily segregated into synthesis and modification processes. Modification techniques are usually considered to be the older of the two. Before the appearance of musique concrete, pure synthesis was more common, but the fundamental goal of most of these early efforts was to build a solo instrument that would fit inco an orchestra.

The goal of musique concrete, on the other hand, was to replace the orchestra and produce works of the magnitude of a symphony entirely by electronic means. Modification methods attack sound from every conceivable direction. Any of the simple sound parameters such as frequency, amplitude, or spectrum may be directly altered.

Time sequencing of the envelopes of these parameters may be altered in numerous ways. Parameter envelopes charac. Even simple judicious selection of short portions of sounds can give a completely different effect. Sound on Tape As mentioned previously, sound on magnetic tape is a physical object that may be freely manipulated. The only tools required are a reel-to-reel tape recorder two recorders are desirable , a good pair of nonmagnetic scissors, a splicing block with splicing tape, and imagination.

A grease pencil is also necessary for marking the exact location of sound events on the tape. A so-called "full-track" tape recorder is very helpful when extensively editing tape. Such machines record on the full width of the tape; thus, it may not be turned over for additional recording time. Although such machines are hard to come by in the consumer new equipment market, they are fairly common as professional equipment. Stereophonic effects are typically added as a separate step later after the basic composition has been completed.

Also the higher tape speeds available are typically used. Besides better recording fidelity, the many pieces of tape to be manipulated will be larger and easier to handle. Rearrangement The most fundamental splicing modification is rearrangement of a previously recorded sequence of sounds.

Since a fair amount of experimentation is usually required, the sequence is typically copied several times before cutting commences. One interesting introductory experiment is ro record a scale from a musical instrument and rearrange it to form a melody.

More interesting results are obtained if parts of the envelopes of notes are removed or attacks and decays are interchanged.

In particular, using just the attack portion of many musical instrument notes can create some very interesting results that usually will not resemble the source instrument at all. A related procedure that works well with full-track recorders is to make an extended diagonal splice rather than the typical short diagonal or straight splice.

The result will be that one sound will seem to dissolve into another. If a piece of tape is spliced in slightly crooked, the high frequencies will be lost on playback and the result is as if a curtain had been pulled over the sound source.

Prentice Hall. Chamberlin, Hal Musical Applications of Microprocessors. Hayden, Rochelle Park, N. John Chowning. The synthesis of complex audio spectra by means of frequency modulation. Journal of the Audio Engineering Society, 21 7 —, Hay- den, Rochelle Park, N.

Musical Applications of Microprocessors , De Furia , Steve. De Furia , Steve and Joe Scacciaferro. PC Publishing technology. Chamberlin , Hal Musical Applications of Microprocessors.