Demonstration of Quantisation Noise and the effects of Dithering and Noise Shaping
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The track "Lavender.wav" was ripped at 16 bit, the gain was reduced by 20dB 
then the track quantised down to 8 bits. 

Why quantize to 8 bits?
We quantize to 8 bits as it is easier to show the effects the Noise Shaped Dithering 
Quantizer produces. We could have done the gain reduction and quantizing down to 
16 bits but the effects would be difficult to hear on a computer setup, to hear the 
difference the file would need to be burned to CD and played on a good quiet system 
with the gain turned up loud.

The effect of the Noise Shaped Dithering Quantizer is the same at 16 bits as it is 
at 8 bits; it increases the dynamic range and lowers the natural noise floor where 
the ear is most sensitive, thus producing a track which sounds much clearer.


What's in the file?
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The Left channel is the results using a Noise Shaped Dithering Quantizer.
The Right channel is the results using a normal Quantizer.
The file has been stored as a stereo file so the channels can be observed and 
compared on a Spectrum Analyser.


When you Play the File, the Left channel sounds much clearer.
This is most easily heard if you listen with a pair of headphones, this lets you 
listen to each channel independantly. Alternatively, comparing the Left and Right 
channels is easy with our Mixing Desk


With our Mixing Desk
--------------------
1. Add Track
2. Depress the Loop button on the Track bar
3. Increase Gain to +10dB (nominally -6dB when loaded)
4. Start Mixing - will start playback

To hear left channel only pan to the left, for the right channel only pan to the right.

The Left channel (using a Noise Shaped Dithering Quantizer) sounds much clearer.



If you want to see what is going on use our Editor

With our Editor
---------------
1. Load the File - File|Open...

   Just looking at the File in the Time Domain, it would appear that the Left channel is noisier, 
   to find out what is going on you need to view the file in the Frequency Domain.

2. Depress the Loop button, forces the file to continuously repeat
3. Start the File Playing
4. Start the Spectrum Analyser - Special|Spectral Analysis Tools|Spectrum Analyser (Ctrl+F)

The Dithered Signal (Left channel) is Red, and the Non Dithered Signal (Right channel) is Blue

It can be seen that:

1. 	The Noise of the Non Dithered Signal is approx. flat.
	The Noise of the Dithered Signal is shaped and shifted above 14kHz where we are less sensitive 
	to it, so it sounds cleaner

2.	The Dithered Signal retains more information, more than 18dB more




For more information on our Noise Shaped Dithering Quantizer, see our site at:

		http://www.glowingcoast.co.uk/audio/theory/Dither/index.htm






