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Created by chris, on November 05, 2010 21:57

Music and Beyond: Psychoacoustics for beginners and runaways

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chris
about 7 years ago
-> Loud, louder, what actually is loud?

Usually when it comes to the discussion how loud something is, soon or later someone mentions dB.

Well, hmmm….

dB is not a unit measure! Some might tell you different but, if we talk about e.g. meters, one can compare to the meter prototype. But what can we compare a, lets say loud speaker with? A prototype speaker? Not at all.

I said dB is not a unit measure – it is a scale, but there are dB-measures. Let`s have a look:

So here x1 is what you want to measure: Some input. While x2 is what you compare with, just like the prototype meter, we have to compare to somthing, of course. And that is why pure dB is no unit measure and where the different dB measures come into play:

  • dBSPL: x1 is 20micropascal, the later is the smallest preassure change humans usually can hear
  • dBv: Comparing to 0.775Volt, the maximum line level
  • and many more…

Well, if we talk about loud, we have to talk about somthing we can hear. So dBSPL is an appropriate choice. But dB do not measure loud-ness, we compare to some preassure and we have an fundamental problem doing that: Our hearing perception is different for different frequencies, d`oh.
50micropascal at 1kHz feels different loud than at 200Hz. The equal loudness countor show that phenomena. Phone is the unit taking this into account. It is derived from dBSPL. Phone does compensate the differences in hearing perception shown by the linked curves.

What else? Well, for measuring that thing loudness one would expect 20 whatever being twice as loud as 10 whatever. Phone do not fearture this! But the unit Sone does. It is calculated out of Phones but in a non-linear fashion.

When you want to know h_ow loud is my dish washer_, especially in comparison the some other washer, or whatever: Sones are the unit to go with!

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