Improving the Signal to Noise Ratio – In Defense of Noise

[This post follows from Improving the Signal to Noise Ratio.]

All signal all the time may not be a good thing. So I’d like to offer a defense for noise: It’s needed.

Signal is signal because there is noise. Without the presence of noise we risk living in the proverbial echo chamber. When we know what’s bad, we are better equipped to recognize what’s good. I deliberately tune into the noise on occasion for no other reason than to subject my ideas to a bit of rough and tumble. Its why I blog. Its why I participate in several select forums. “Here’s what I think, world. What say you?”

Of course, noise is noise because there is signal. Once we’ve had an experience of “better” we are then more skilled at recognizing what’s bad. I remember the food I grew up on as being good, but today I view some of it as poison (Wonder Bread anyone?) And there are subjects for which I no longer check out the noise. The exposure is too harmful.

There are subjects for which I seem to be swimming in noise and casting around for any sort of signal that suggests “better.” I’m recalling a joke about the two young fish who swim past an older fish. The older fish says to the younger fish, “The water sure is nice today.” A little further on, one of the young fish asks the other, “What’s water?” I’m hoping to catch that older fish in my net. He knows something I don’t.

To understand what I mean by noise being necessary it is important to understand the metaphor I’m using, where it applies and where it doesn’t.

Taking the metaphor literally, in the domain of electrical engineering, for example, the signal to noise ratio is indeed an established measure with clear unit definitions as to what is reflected by the ratio – decibels, for example. In this domain the goal is to push always for maximum signal and minimum noise.

In the world of biological systems, however, noise is most definitely needed. One of many examples I can think of is related to an underlying driver to evolution: mutations. In an evolving organism, anything that would potentially upset the genetic status quo is a threat to survival. Indeed, most mutations are at best benign or at worst lethal such that the organism or it’s progeny never survive and the mutation is selected against as evolutionary “noise.”

However, some mutations are a net benefit to survival and add to the evolutionary “signal.” We, as 21st Century homo sapiens, are who we are because of an uncountable number of noisy mutations that we’ll never know about because they didn’t survive. Even so, surviving mutations are not automatically “pure” signal. There are “noisy” mutations, such as that related to sickle cell anemia. Biological systems can’t recognize a mutation as “noise” or “signal” before the mutation occurs, only after, when they’ve been tested by the rough and tumble of life. This is why I speak in terms of “net benefit.”

For humans trying to find our way in the messy, sloppy world of human interactions and thought, pure signal can be just as undesirable as pure noise. I’ll defer to John Cook, who I think expresses more succinctly the idea I was clumsily trying to convey:

If you have a crackly recording, you want to remove the crackling and leave the music. If you do it well, you can remove most of the crackling effect and reveal the music, but the music signal will be slightly diminished. If you filter too aggressively, you’ll get rid of more noise, but create a dull version of the music. In the extreme, you get a single hum that’s the average of the entire recording.

This is a metaphor for life. If you only value your own opinion, you’re an idiot in the oldest sense of the word, someone in his or her own world. Your work may have a strong signal, but it also has a lot of noise. Getting even one outside opinion greatly cuts down on the noise. But it also cuts down on the signal to some extent. If you get too many opinions, the noise may be gone and the signal with it. Trying to please too many people leads to work that is offensively bland.

The goal in human systems is NOT to push always for maximum signal and minimum noise. For example, this is reflected in Justice Brandeis’s comment: “If there be time to expose through discussion the falsehood and fallacies, to avert the evil by the process of education, the remedy to be applied is more speech, not enforced silence.” So my amended thesis is: In the domain of human interactions and thought, noise is needed by anyone seeking to both evaluate and improve the quality of the signal they are following.

A final thought…

If we were to press for eliminating as much “noise” as possible from human systems much like the goal for electrical noise, I’m left with the question “Who decides what qualifies as noise?”