91Èȱ¬

We're now ready to . We've created a which, while we wait for the Web Audio API to gain wider adoption, works best in . You can play with the four machine simulations, learn more about how they were used at the Workshop and then study the code to find out how they were built. Let's take a brief look at each of the machines in turn:

Wobbulator

, a sine-wave generator with a controllable modulation frequency, was used in the workshop to create a variety of space-y sounds. The device itself wasn't intended for musical use, it was a piece of salvaged equipment designed to make acoustic measurements.

In of the device, we've paid visual reference to some archive photography by retaining the large central frequency control knob. We've taken a couple of liberties with the other controls on the device, including adding a waveshape switch (to allow Sine, Square or Sawtooth waves to be produced). This switch was certainly not present on the original. In our original prototype of the wobbulator we used custom Javascript code to create the signals, but with the addition of the OscillatorNode to the Web Audio API the .

Ring Modulator

Ring Modulation is an effect achieved by multiplying two signals together. In of the effect we wanted to show how this effect was used in the early days of the Radiophonics Workshop to create the voices of the Cybermen and Daleks in Dr. Who.

The Radiophonic Workshop provided the TV studio with a Ring Modulator and a tape machine with a recording of a 30Hz sine wave on it. This provided one signal while a microphone provided the other. The Ring Modulator box contained an analogue circuit which multiplied the two signals.

Our captures some of the characteristics of the orignal device by modelling the diodes with a . The bias of the diodes can be adjusted with the "distortion" control - a feature not present on the original ring modulators. You can also adjust the speed of the simulated tape machine to change the pitch of the modulation frequency.

If you're running see if you can discover how to use the microphone in your computer to create your own Dalek voices! might help you to figure it out.

Gunfire Effects Generator

The was a piece of equipment that pre-dates the Radiophonic Workshop, but since it appears in the 91Èȱ¬ Engineering Monograph "" and it's a fun piece of kit we thought we'd include it in our work. The device was designed to replace the use of real guns in recording studios as these guns "occasionally 'misfired' (disastrous in a tense situation) … scared the performers, and required a special licence … to comply with 91Èȱ¬ Office regulations".

We based our demo on the given in the . We decided to use a buffer containing a burst of white noise in this demo, but also show how you can use the to create a custom white noise generator. This noise is gated and filtered as described in the monograph. We also add a little reverberation to simulate the sound the device would make in a small room.

Tape Loops

Longer compositions at the Radiophonic Workshop were created by manually splicing tapes together and combining multiple tape machine tracks. Delia Derbyshire in an interview. Our demo of combining multiple tape loops in time to create a piece of music. You can adjust the playback speed of the tapes, either by a fixed amount (halving the speed) or by a small percentage. The small percentage change is useful to "beat match" the loops.

This demo is quite simple but and load data into audio buffers using the Web Audio API.

Summary

We hope you enjoy playing with the demos we've created and learning more about the capabilities of the Web Audio API. If you're a developer, or have an interest in the future of audio on the web, we encourage you to with the W3C working group, or to build, and share with us in the comments, some exciting audio applications yourselves: hopefully our code will provide you with a good starting point.