🚀 go-pugleaf

The various noise shaping options usually serve to gradually shift the dither noise out of the sensitive area of our hearing and up into the ultrasonic regions instead.
Option A is the most general type, and the most audible.
The further up you go, the less dither noise is audible.

The thinking behind this is to hide the quantization distortion incurred when reducing the bit depth of an audio file, as simple truncation will result in rounding errors - and very probably noise.
Dither adds a more pleasing noise instead.

The only times you do not need dither is when you are not altering the bit depth of the file in any way. If you process with Audition, then it will be using floating point operations to do any effects, and dither may or may not be needed if your source files are at 16 bits. If you are working at 24 bits or Floating Point resolution, and wish to put the end results onto a CD then dither is required.
If you are working in 24 bit and are outputting to DVD-Audio, dither is not required if your DVD-A is going to be 24 bit.

I hope this helps a little, and if not then please post back and someone will help.