sound quality problems

[elcid01]

I recorded sound (speach) elements for a number of slides. The sound quality was good.
Than I added background music from a Macromedia sample file (Loop Acoustic Mellow.mp3). The sound quality of my oral explanations dropped dramatically. I removed the background music. But quality level remained the same and I cannot go back to the initial level. Is this a common phenomenon? Should I rerecord the sequences.
Thanks

[elcid01]

Forgot to mention: the loss of quality does not occur in the dev environment when previewing slide or movie. It gets substantially worse when comiling into a standalone exe file.

[Timbre4]

You need to watch closely - a) recording resolution (sonds fine if you are happy with it), b) resolution of background (included loops are lower resolution mp3; you can import better), and most importanly c) resolution for final output.

It may be that your narration audio is reduced to the same resolution of the background audio (or worse?) and then you're wondering why it happened. The presence of the background loop is not the issue. I've experimented with this.

Hopefully you can go back to the original project and render it again, watching the audio output spec. To keep file size down, tons of audio can get thrown away. This is okay to a point; make sure you haven't drifted down to 8 bit resolution which is unacceptable. Have done tons of work at 11K sample rate mono 16 bits...