Dynamic Performance Vs Static Performance.

SOULNOTE Chief designer Kato continues his series of essays on design philosophy with dynamic performance vs static performance.  “I believe that dynamic performance is more sensitive to hearing than static performance because it is an important function for survival that has been imprinted in human DNA since primitive times. I would like to present some examples that suggest this. This is only my hypothesis.”

Moving prey can be seen clearly.

It is said that the eyesight of a hawk in the sky is dozens of times better for moving objects than for stationary ones. Now, not only hawks, but we can easily spot moving objects, can’t we? So wave your hand in a crowd to make yourself easier to find, or even Wally is easy to find if he is moving. Things that move are easy to find. Isn’t it obvious? No wonder this applies to hearing as well. Crack! This sensitivity to impulsive sounds (dynamic sounds), such as knowing the direction of sound, must have been a necessary function for obtaining food since ancient times.

To protect oneself from enemies.

In primitive times, people were attacked by enemies mainly at night. This was because they could not see well at night. It is believed that hearing was very important to protect oneself from enemies at night. It can be imagined that those who sensed the presence of an enemy’s footsteps and direction and fled were the ones who survived. In other words, it is natural that the human ear is sensitive to impulsive (dynamic) sounds. And it is that fast-rising sound that is the dangerous sound that we should listen to intensively. Static sounds, on the other hand, are less dangerous and do not require as much sensitivity.

Humans cannot hear sounds above 20 kHz, but

But that is the case with sine waves. In the case of a continuous sound like a sine wave, there is no danger and no need to increase sensitivity.
Consider the case of cutting the band above 20 kHz because sine waves cannot be heard. This is a common technique used in audio products to improve the signal-to-noise ratio. In this case, the static performance value is better because the noise component is reduced. However, the rise of impulse sound will be slower. In other words, dynamic performance will be reduced. It is natural for humans to perceive such sounds as insignificant and unrealistic. This is because we do not immediately perceive them as dangerous. 

LPF kills sound.

If human hearing is sensitive to dynamic sound, then static performance-oriented audio equipment (LPFs) that easily cut high frequencies outside the audible bandwidth is a major problem. Why don’t people realize this? Even engineers must feel a loss of reality when listening to sound. However, they are misled by the numbers and think in their minds that the less noise, the better the sound. Or perhaps they are not listening to the music when designing. Either way, engineers assume that as long as the numbers are good, the S/N ratio is good, even if the sound is boring and without reality. This is also the curse of Fourier.

Digital arithmetic kills sound.

More serious are digital operations such as oversampling digital filters and digital PLLs. Digital arithmetic is not mathematically wrong, and many would consider the evolution of digital arithmetic to be the evolution of digital audio over the past 40 years. I used to think so too until a few years ago. Indeed, mathematically correct. However, that assumption is dubious. Humans cannot hear above 20 kHz, so it doesn’t matter what we do. This is the premise of digital audio. It is too reckless.
To me, it seems to fatally undermine reality even more than the LPF. I am sure you will understand. But engineers are so blinded by the excellence of static performance that they don’t notice it. This is also Fourier’s curse.
As I wrote last time, SOULNOTE’s digital instruments allow you to switch between NOS mode and FIR mode for comparison. You will see how digital manipulation can kill the sound. Even if you can’t tell the difference, it proves that bypassing the digital filter makes less difference to the sound than you might think. Even though the distortion can be as much as 400 times greater!
Digital sounds great without digital manipulation. It is not digital that is bad. It is the digital operations that ignore the characteristics of human hearing that are bad.