The BBC sound system has long been recognised for its versatility and powerful Envelope control structures. Joining a long list of books on the subject is Creative Sound, which is accompanied by a suite of 31 programs on cassette or disk. Considering the age of the BBC 'B' micro and the amount written on the sound system, it seems at first sight a little late in the day to release 'yet' another book on music and sound. However, with both authors having an impressive track record (Chris Jordan designed the SOUND & ENVELOPE statements for BBC BASIC), it seemed worth a look.

The authors have made the assumption that the reader is acquainted with the SOUND and ENVELOPE commands and do not waste pages re-explaining these commands. This is entirely reasonable as these can be gained from the User guide or any number of sources. However programs are included which help the user to get to grips with these commands, the ENVELOPE statement causing the most difficulty to many people.

The basics out of the way and a lightning guide to electronic sound synthesis covered, Dave Ellis and Chris Jordan then tackle the problem of entering musical data in a format that the micro can understand. Here they introduce their favoured method of entering data - a Musical Composition Language (MCL) - one that is similar to AMPLE, familiar to users of the Acorn Music 500, (see page 40), which is hardly surprising as Chris Jordan also designed the 500! The MCL crops up in many programs and is far more sensible than row after row of meaningless numbers. Unlike the 500 where the use of AMPLE has arguably strong and weak points, the BBC as a standalone machine with a relatively simple sound system and no appropriate musical keyboard, needs an easier way of entering data from the QWERTY keyboard and the MCL is a most appropriate method.

Besides a 'Music Interpreter' to accept data typed in (ie A,C,E etc), the authors also look at two further ways of inputting music. Firstly the obligatory "Recording Keyboard' program which turns the typewriters keys into a miniature keyboard with recording/playback facilities and a musical 'Simon' game ("Simon says...").

This is on the face of it might not seem too exciting but even in this program the authors have not taken the easiest and quickest route by merely using random note generation. Instead they have applied a few simple rules that makes the tunes generated more bearable though maybe not that memorable!

Chapter 5 concentrates on creating sounds and contains an envelope generation program which is far from new, but essential. A marked feature of all the programs in the book is that there is little emphasis on powerful graphic displays. This is reasonable as the BBC does, at times, use up vast chunks of memory on graphic displays. However I was disappointed that the graphic capabilities weren't exploited more fully as this generally aids the running of programs and learning of specific principles. But this chapter did contain one noteworthy program which utilised graphics in both a simple and very effective manner. The 'Partial Timbres' program allows the user to change the timbre, not by typing in new values but by re-shaping the envelope graphically onscreen.

There follows a short chapter which is aimed at the 'lazer-zap' enthusiasts and seems an excuse for getting rid of a few off the shelf sound effects. This adds little to the book and would have been far better left out.

The authors then turn their attention to 'live' music and extend the 'micro-as-keyboard' philosophy to present a suite of programs which combine the live 'play' element with programmable sound synthesis, sequencers and echo-sounds.

Chapters 8 and 9 take up composing as the main theme and this provokes some detailed discussion on building composing machines. Mozart's Dice Game appears as a major program and is well worth looking at, so long as you don't mind waltzes. One program that caught my eye (not my ear!) was the 'Composing Grid'. On running the program the screen hits you with a mass of letters, numbers and arrows which turns out to be a well organised grid of 10x13 cells. Essentially it combines the random choice element with controlled input from the user and is halfway between total human creative composing and random-based micro composing. It does work and has to be seen to be believed!

The final program in aiding the composer is a music compiler, which returns the MCL format and allows the user to compose up to four part music. Besides the compiler there are several demonstration pieces which makes good use of the sound chip.

The concluding chapter looks at a subject often missed, that being the use of a micro as a teaching tool for music. Ellis and Jordan provide seven programs that test the listener for pitch, key signatures and sense of rhythm. The programs are good simple examples of how to utilise the micro in a music-teaching oriented situation. It's highly unusual to see educational uses for micros in music encouraged in a book of this nature and it's very much to the credit of the authors.

Throughout the book the authors take a middle path on explaining programs. Sufficient information is given on the main structure of the program but fortunately it is not so oppressively detailed as to obscure the points they are making. There is an assumption that the reader is a competent programmer and certainly more than a passing knowledge of BASIC is needed. However in itself, the book and especially the tape/disk make a package that is usable by any BBC owner.

But the book is very much written by musicians for musicians and thank goodness doesn't waste space with over-simplified explanations. There is little doubt that both authors know the subject well (as would be expected) and cover the ground well with a fair amount of historical content. Buying the book with the programs on cassette or disk is an absolute necessity, unless you have infinite patience and can type seemingly endless rows of data.

The only weak point is the late release of such a book. Virtually everything that can be said about the BBC sound system has already been said and adding to the wealth of available material may seem fruitless. Despite that fact, Creative Sound is of a higher standard than most other attempts at books in this area. It might be late, but it has been worth the wait.

Price: Book (£9.95) Book/Tape (£17.95) Tape/Disk (£19.95)

Contact: Acorn soft (0233) 316039