The cleaner the talking audio the better the reaction on the talking skull.  Optimally the "talking" should have no effects applied to it (such as echo and background noise).

 If you have ambient audio (such as music or noises) that you also want to play then you will have to play it from another audio source or split left/right stereo channels from one stereo source.  To split the channels you first need to record a stereo audio file with the "talking" on one side (left or right) and the ambient audio on the other.  We use a free audio editor called Audacity to do this:

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You then need to use audio cables to split stereo into two mono channels (left and right).  Send one mono side to the PicoTalk in the talking skull and the other to wherever you want to play your ambient audio.