Noise - the sneakthief of musicality

I recently came across this phrase "dynamic noise floor" here on MonoandStereo.com

I would like to present the subject of “Dynamic Noise Floor” to our readers. There is much confusion in both audiophile and engineering circles... So I shall say, there is noise floor, the static one you can measure with ease. It is static, and unless very high in level, benign and does not impede the enjoyment of music replay.

 

Then there is “Dynamic Noise Floor” as coined by Robert Koda – DNF. Not so much a noise but rather a gritty and shifting ghostly shadow, a clogging mush that is changing in a continuous and dynamic way yet somehow related to the music in a sickly fashion.

 

It stems from the music itself when passed thru a piece of electronics or system. It is the ultimate corrupter and its nature is a direct result of a multi fold of complex interactions occurring within the make up of the circuitry. It may manifest its self in transients, or perhaps decay. Specifically in every event and every moment of music. It is our opinion that DNF is the single greatest contributor to the inferior sound of a components that otherwise “measure” so well. DNF is perhaps the Achilles heal of modern electronics.

Much, if not all of the DNFs make up is spread across the time domain – An occurrence in the past effects the result of the near future. As you can imagine, the effect has catastrophic consequences on music replay!

 

Robert Koda realised the existence of a musically modulated and ever changing Dynamic Noise Floor decades ago.

He states in another interview "The measurement of a "dynamic noise floor" matters more but this is not easy to measure."

We are all familiar with ‘noise’ (distortion) in photography that often appears as graininess. In a dynamically changing signal, such as TVs, we see this noise or distortion in various ways -  blockiness, grey areas, etc. All these distortions or noise are at a low level but make us acutely aware that what we are looking at is processed - it disturbs any illusion of realism.

Similar to vision, hearing is a complex sense but there are many differences, apart from the obvious, which auditory research is gradually uncovering. We know we can’t freeze a sound frame and examine it as we can with a video frame - with sound, the brain is continually processing the changing signal it’s receiving from the ears. The processing of these signals leads to our perception of an auditory scene, much as we perceive a visual scene.

 

In the auditory scene thus created, we perceive auditory objects which we can keep track of from moment to moment. If our playback systems reproduce everything without distortion/noise (from very loud to very quiet), we perceive this as a realistic illusion, much like TV/video/film can produce a realistic illusion.

 

Anything that disturbs low level signal reproduction, including low level noise, disturbs our illusion of ‘realism’. The aspects where this is most noticeable are in the perceived dynamics of the reproduced signal and in the depth, layering & solidity of the soundstage. When these areas are realistically portrayed the improvement in the perceived sound leads to a better understanding of the interplay between players and ultimately into the emotion and musicality of the reproduced musical event (if this is in the recording).

 

An interesting and important aspect is that this noise isn’t audible when there is no signal - it’s not an audible layer like tape hiss or vinyl groove noise. It’s low level and fluctuates with the dynamic signal being processed. As a result, measurements of this low level dynamic noise correlated with the signal, prove elusive. However, we can see examples of noise modulation in the datasheets of some DAC chips.

 

We often don't notice when our systems have such low level noise issues as it only becomes evident when removed and all of the above improvements are heard - hence the term 'sneak thief' - it's robbing us of these aspects without our noticing it.

 

The other interesting and important aspect of this is the significance of such low level signals to our auditory perception. We pay particular attention to the rise time (attack portion) of sound and use it primarily to characterise our perception of sound. My understanding leads me to believe that a large part of the explanation is due to the importance of this rise time in our perception of sound.

 

All of this meaning is contained within the phrase “Noise is the sneakthief of musicality”