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Guide to Electronic Music Techniques


Basic Tape Techniques



Most people are familiar with the tape recorder as a means of storing and recalling sounds, but the tape recorder can also be a powerful means of transforming and manipulating sounds once they have been stored. Much of the earliest work in Electronic Music and Musique Concrete relied almost entirely on a few basic techniques for manipulating recorded sounds.

Before examining these techniques it is necessary to go into a few points about different types of tape readers, as some machines will make make of these operations difficult (although probably not impossible if you use a bit of ingenuity). First of all, it is desirable that your tape recorder runs at at least two speeds (if more than two, so much the better). Secondly, it will be necessary to get access to the play-back head of the machine for editing purposes (See Figure 1). On some machines this can be difficult, but removing some of the head covers usually make it possible. Another problem with editing on some machines is that the playback head is inoperative unless the recorder is in 'Play' mode. You may be able to get round this by running the tape the wrong side of the capstan shown in Figure 1 (try it, the first time with a bit of tape you don't need, in case of disasters!). Lastly, there is the technical matter of head configurations.

Figure 1. Tape head arrangement.


Many domestic tape recorders are designed so that two programmes can be recorded, one in each direction of the tape, in order to save on tape costs (all cassette recorders use this approach). While this may be fine for some applications it is undesirable for this sort of work for two reasons: first, if you are going to edit the tape, it is not much good having another programme going the other way, and, second, one of our most powerful transformations, reversing the material, is impossible on a machine designed specifically not to do this! Figure 2 shows you why). If your machine records in this way then you will probably have to resort to some sort of modification, for example, some machines have room to fit an extra playback head. If your tape recorder has some or all of these drawbacks, don't despair, get to know the idiosyncracies of your machine and learn how to get round them (or even turn them into advantages). Obviously if you have a more professional machine the scope is wider (and two machines are more than twice as good), but part of the idea of this sort of music is doing what you can with what you have available. A lot amazing things have been done with the most primitive equipment.

Figure 2. Track configurations


The only other items you will need for the experiments below are microphone, splicing gear and some imagination.

So, what are the possibilities?

If you have recorded a sound, or succession of sounds, it will be represented on tape as a magnetic analogue of the original waveform. Normally one would want to reproduce these sounds in a manner closely approximating the original. But, having stored this information, there are other ways of reproducing it. For example, if you replay the tape at a different speed, a number of things are altered. If you replay something faster the tempo will be quicker and the pitch higher, but other, less obvious, changes will occur. If you try this with singing you will find that the characteristic vibrato is speeded up producing the "Chipmunk" effect; or, if you slow it down, the vibrato becomes a slow wavering of pitch — try it. Also you will find that different timbres can be produced — a slowed-down soprano does not sound like a tenor, a speeded up bassoon does not sound like an oboe; also, slowed down high-register guitar is different to low-register guitar, and vice-versa. This is caused by the particular resonances of the instruments concerned, but don't get tied down in the technicalities, experiment with the sounds.

The second technique is reversing the tape. Naturally events now occur in the reverse order, but what effect does this have on the sounds? Much of what the ear understands about sounds is concerned with envelope — the way sounds change in time. In other words we interpret things in relation to what happened last. So if we reverse those envelopes our perception of the sounds can be altered drastically. For example, a single sustained note on a piano is characterised by a sharp attack and a long, exponential decay. Reverse it and a very different sound occurs. One of the characteristics is that the upper harmonics die away more quickly. In reverse you can hear these harmonics gradually coming in (Figure 3) followed by a 'clonk' at the end (the attack) — try it.

Figure 3. Simplified diagram of piano envelope (all percussive sounds are essentially similar).


Or reverse some ordinary speech — not only does it not make sense but it sounds like a completely different language — why? The characteristic inflections and the envelopes of the sounds are reversed. Another idea — try to record speech so it will be intelligible in reverse (by speaking the words in reverse) — it's hard — and the results will make the Daleks seem quite human!

Next, you can extract particular sounds, groups of sounds, or particles of sounds from their contexts and rearrange them into new contexts. For example, tape a passage of speech and try to separate the vowels onto one tape and the consonants onto another — if you don't know how to separate them listen to the tape at reduced speed — these techniques can help you to learn about sounds as well as manipulate them.

This leads to the concept of editing, or joining together, sounds from different tape sources. Any sound (or part of a sound) that can be extracted from one tape can be spliced to any sound from another tape and this is where composition comes in. Try to build those sounds you've found into something that means something to you.

Let's look at two things that might help. If you can join bits of tape together, you can join them into a continuous loop and this loop can be (within reason) any length from fast repeated notes or figures through ostinatos to extended passages; or loops may be speeded up drastically to produce new timbres — try this over several stages.

Finally, you will want to superimpose one set of sounds onto another. How you do this will depend on the facilities you have available. If you have a twenty-four track recorder you can simply record each layer onto a different track, and mix it down, but, assuming that you have more humble facilities, as long as you have some way of copying one recorded track onto another and mixing in new sounds (many tape recorders provide for this) well then, the sky's the limit — think about it!



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Sound on Stage

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Electronic Dream Plant Limited


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - May 1981

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