Visualizing sound in TouchDesigner

You can follow this tutorial to generate a dynamic sound wave in TouchDesigner starting from a sound file.

Importing your sound file into TouchDesigner

• Open TouchDesigner
• Remove the example network and get a blank view
• Add your sound file: you can do this by directly dragging it inside the software view. It will automatically create a Audio File In named as the original file. Alternatively, you can add a Audio File In CHOP by double clicking on the pane view. You can then select your file from the operator menu.
• Add an Audio Device out and link it to your sound file. In this way you will be able to hear it. A file on its own will not automatically play without it.
• You might have noticed how the program is already giving you a visualisation of the audio file. Add a Audio Spectrum CHOP to display the frequency spectrum of the audio file.
• By default you will see the audio spectrum as a stereo view, visualising the two channels. You can turn this into one by adding a Math CHOP.
  In the menu you should set:
  Combine Channels : Average
  This option will merge the two channels into one.

Turning the CHOP view into an image

At this point you are seeing the audio spectrum of your file as a single graph. This image though is only the visualisation of a CHOP operator and not an image. CHOPS only understand channels of numerical data. We now need to turn this into an image - in this case a TOP.

• From the exit point of your last Math block right click to see which operator can be link to it. We will select a CHOP to SOP. SOPs are are operators that can generate, import, modify and combine 3D geometries. We are using this to be able to translate the axis diagram into an image.
  In the menu you should set:
  Channel scope : chan1
  (the channel name of your Math CHOP)
  Attribute scope: P(1)
  (This option will only select the Point Position on the Y Axis, the one we need to visualise)
• Connect the CHOP to SOP to a Geometry COMP. Do it by right clicking on the exit point of the last operator.
• Double click on the pane and add a Render TOP. You use this to render all 3D scenes. By default it will link to your geometry. At this point the graph is not visible. To make it visible we need to add a Camera and an Ambient Light COMP. They will both connect to the Render automatically. Now you should be able to see your sound wave image at the center of the Render TOP.