Combustion is seldom a steady process. Most flames oscillate in the sub-audio region; singing flames and some pyrotechnic compositions whistle at much higher frequencies. Daedalus now hopes to tame such oscillations for entertainment purposes. Combustion energies are so high that even a modest rate of burning could generate intense sound.

DREADCO's chemists are now exploring this idea. Their pilot project is simply a firework consisting of alternate layers of fast-burning and slow-burning composition. As the combustion zone moves down through the layers, the gas-pressure generated by burning will be modulated, and the firework will howl out a predictable tone. But how to record an audio signal on such a firework? An electrolytic process seems hopeful. A stick of pyrotechnic composition, dampened to make it conducting, will be passed between a pair of electrodes carrying the analogue audio signal to be recorded. With suitably ingenious chemistry, the density of ionic deposition at each point will control the rate or gas-output of burning at that point. Even with a sonic efficiency of a few per cent (about as good as most loudspeakers), such a ‘sound-stick’ could deafen its audience with hundreds of watts of sound. The technology would be ideal for public musical performances, and also as a fire alarm. A suitably encoded sound-stick, lit by the blaze, would bellow out its location and appeal urgently for help.

Seeking a milder and cheaper version of the idea, Daedalus recalls the old trick of painting a track on a piece of paper with potassium nitrate solution. When later ignited, the track is revealed by a smouldering glow which travels along it. He proposes to print such a track on paper in directly digital form, as minute dots of oxidant scaled in binary intensity. When lit, the combustion zone would speak the digital signal as it traversed its ‘sound track’. Audio burn papers, each with many sound tracks, could be printed in large numbers cheaply and easily.

This elegant technology will combine utter simplicity with a useful sound output. Even a few watts of glow will make a respectable noise. Each track can be played once only, of course, but a paper could carry many tracks, and a music-lover could carry many papers. His inventory of pestilent personal electronic gadgets — mobile phone, pager, calculator and so on — would at least be reduced by one.