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Getting Started with Mouth Synchronization

 

Question:
Does anyone know where I can find the prints on how to built an 'auto-talk' circuit? 

 

Answer:

I've built animatronics for many years and experimented with every kind of voice operated relay system, and come to the absolute conclusion that if you want good mouth movements, you need to carefully place the signals when you want it to open and close to coincide with your audio.  That’s for many reasons.  Just using amplitude alone will give mixed results since amplitude does not always equal "syllables".   Also, there will inevitably be variations in the audio even if the audio has no music or sound effects mixed in, which, of course, completely ends any effectiveness of a VOX.  The real magic in my animation over the years was the accurate sync of the mouths.  Placing the signals is another art and would take a much larger discussion, but to get started with this simply, I suggest that you start the same way I did, using the 567 tone decoder that you can probably still buy from radio shack.  Use the application notes to build the simple little circuit and place a tone on a tape on an adjacent track to your audio every time you want the mouth to open.   For example – I am talking about your using two tracks of tape for your first experiment.  Using a tone generator, connected to a button, place a tone on one track of tape to coincide with when you want the mouth to open.  On the other track of tape is the audio.  If you don't have the capability of multi-track recording yet, you can use a simple cassette recorder to experiment with and record the audio and the tone track at the same time.  The important thing to do is to tune your tone decoder to whatever frequency you chose.  I did allot of work on this in the 70's and found I was able to get 5 tones on a track of tape and the first big shows I produced actually used 4 8-track tapes players, all started at the same time, with 5 tones on each track to run all the movements.  When you get further into this, there are better techniques, but this is the best way to run simple animation with few movements.  (PC based multi track should work well).