There has been discussion elsewhere in the forum regarding the effects of noise floor modulation in DACS. Unfortunately its got a little buried in other side nonsense, so this is a thread to discuss the issue.
To apply the descriptive terms used previously, this effect is a change in the noise floor that is correlated to the dynamic music signal in frequency and amplitude.
So, what are the audible effects of such a distortion? One poster has described the audible effect as a loss of dynamics. Otherwise there is little else to go on. As such I decided to create simple listening test which is described as follows.
This was conducted using modified versions of a 24bit, 96kHz track - Saint Seans Danse Macabre.
I used Adobe Auditions distortion effect to add a pathological level of harmonic distortion to the original file.
I then inverted and subtracted the original file from the distorted version, trying to leave only the distortion behind.
This distorted file was then adjusted in level, two versions one peaking -**dB and one peaking -**dB (overall level).
This was then mixed back into the original to create 2 files with different levels of "noise floor modulation".
This distortion is correlated to the original both in terms of level and frequency content. I am not saying this is a definitive NFM test, but I think its a good start to understand if people can actually hear anything going on.
The files are below. If people can PM me their observations rather than post them in the thread we can avoid influencing each other. I will anonymise the comments when I report back. I will tell you the levels and which file is which then.
Have fun
http://gofile.me/2vnEF/hO4u99Ykj
To apply the descriptive terms used previously, this effect is a change in the noise floor that is correlated to the dynamic music signal in frequency and amplitude.
So, what are the audible effects of such a distortion? One poster has described the audible effect as a loss of dynamics. Otherwise there is little else to go on. As such I decided to create simple listening test which is described as follows.
This was conducted using modified versions of a 24bit, 96kHz track - Saint Seans Danse Macabre.
I used Adobe Auditions distortion effect to add a pathological level of harmonic distortion to the original file.
I then inverted and subtracted the original file from the distorted version, trying to leave only the distortion behind.
This distorted file was then adjusted in level, two versions one peaking -**dB and one peaking -**dB (overall level).
This was then mixed back into the original to create 2 files with different levels of "noise floor modulation".
This distortion is correlated to the original both in terms of level and frequency content. I am not saying this is a definitive NFM test, but I think its a good start to understand if people can actually hear anything going on.
The files are below. If people can PM me their observations rather than post them in the thread we can avoid influencing each other. I will anonymise the comments when I report back. I will tell you the levels and which file is which then.
Have fun
http://gofile.me/2vnEF/hO4u99Ykj
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