Noise

It is difficult that the perception of noise differs slightly from person to person.

What doesn't bother one owner may be extremely bothersome to another, and there can also be differences in perception between the manufacturer and the owner.

Even if the manufacturer thinks it is white noise, the owner actually using it may feel it is not white noise.

It is best if there is no noise at all, but there are things that appear in the data...

It is difficult...