[UnkieXeon]

Hey guys and gals,

I would like to point out an issue that can happen when using a microphone/soundcard that records audio with a DC offset. What this means is any audio recorded with this type of microphone/soundcard will place the audio waveform below or above the zero crossing and in essence create a click or pop at the beginning or end of an audio file. Adding silence to remove the pop/click only make s the issue worse as this will create what is known as an audio spike forcing the wave to quickly jump back to the zero crossing. I have included images of this issue below. Please note this is NOT an issue with the Articulate software but instead how a microphone of this type introduces a current to a signal while recording. Typically this issue is caused by a sound card but not always the case. use the images below and the Audio Editor in Articulate Presenter '09 to help determine this issue.

The Red line in the image below shows the audio waveforms true center. As you can see this is offset from the zero crossing (grey line).



The 2 images below are a zoomed in section of the DC offset where the red line is the zero crossing. Again you can see the audio’s true center sits below the zero crossing.

The picture on the right shows what happens to the audio waveform when you attempt to silence the audio. All silenced audio will return to or lay on the Zero crossing but will create a spike where the silenced audio ends (yellow dotted line). This will inevitably cause the audio to pop or click at this point. If there is audio on a slide before this silenced section a pop/click will be heard at this point as well.



Hope this helps.