We have some 16bit/8000HZ/Mono/PCM .wav files, we need to convert to 8bit to use in our telephone system.
But after conversion, we found there're many noise appeared in the 8bit .wav files even if the whole source sounds are silence. (You can use Audacity to generate silence, export it to 16bit Microsoft WAV, then export it to 8bit Microsoft WAV (Other uncompressed files), to listen what happened).
I've tried Audacity、sox、CoolEdit(trial) to do such conversion, they all produce noised after conversion.
How this happened? And is there a way to avoid this?
Best Answer
It is possible the noise you are referring to is dither. Many bitrate conversion algorithms will add dither, which is low amplitude, often frequency-shaped noise to the signal before the conversion. This noise actually increases the audible quality of conversion in most cases. If you don't want dithering, hopefully your application preferences will let you disable it.