Why Is 0 dB Considered the Maximum Recording Level in Digital Audio?

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Discussion Overview

The discussion revolves around the concept of 0 dB as the maximum recording level in digital audio, specifically in the context of dBFS (decibels relative to full scale). Participants explore the implications of this definition, its relationship to real-world sound levels, and the logarithmic nature of decibels.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes that 0 dBFS represents the maximum amplitude before clipping occurs in digital audio programs like Adobe Audition.
  • Another participant explains that decibels are defined logarithmically, where 0 dB occurs when the measured intensity equals a reference intensity.
  • A different viewpoint suggests that 0 dB in digital audio is not equivalent to 0 dB in the real world, indicating it is an arbitrary maximum amplitude for recording.
  • One participant emphasizes that decibels represent a ratio between two levels, and without a reference point, a single dB value is meaningless.
  • Another participant clarifies that for sound levels, 0 dB is often set to the threshold of hearing, while for recording levels, it is set to the maximum recording level, leading to negative dB values for all recordable levels.
  • There is a mention of the bit depth in CDs, where 0 dB is the maximum level, and the lowest level is significantly below this, illustrating the logarithmic scale of dB.

Areas of Agreement / Disagreement

Participants express varying interpretations of the meaning of 0 dB in digital audio, with some agreeing on its role as a maximum recording level while others question its equivalence to real-world sound levels. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Some participants highlight the dependence on definitions of dB and the reference points used in different contexts, indicating that the understanding of 0 dB can vary based on the framework applied.

henry2221
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Recording on the computer physics question?
The meters show signal levels in dBFS (decibels below full scale), where a level of 0 dB is the maximum amplitude possible before clipping occurs in a program such ad Adobe Audition.

However my question is why 0 db? When 140 db is the painful amount and etc.? Why can't it be any higher than 0
 
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well decibels are defined as [tex]log(\frac{I}{I_0})[/tex]
now, if [tex]I_0=I[/tex] then this log is 0, [tex]I_0[/tex] is the limit in your program..
 
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I'm guessing that 0 dB on that program is not the same as 0 dB in the real world. On the program, 0 dB is a somewhat arbitrary amplitude which defines the maximum.
 
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dB is a difference between 2 levels.
If only a single dB figure is quoted it is relative to some agreed level, in sound this is usually 0 power ie, no sound and a positive dB number above this is quoted.

It's just as valid to quote a -ve dB figure representing the level relative to the maximum measurable power.
 
The program shows the dB level going from negative infinite to 0. None of the responses above really tells me much. Can someone please make it clearer.
 
Ok will try again.

dB is the ratio between two values. It's meaningless to talk about the dB of a single level unless you know what you are comparing it to.

For sound levels it is common to set 0dB to the threshold of hearing, then 120dB is about the maximum you can hear before you go deaf.
For recording levels it is common to set 0 dB to the maximum recording level, then all recordable levels are below this and so have negative dB, in logs fractions of a number are negative.

So in a CD with 16bits of range with 0dB being the maximum level, then the lowest level will be 96dB below this, or -96dB.

Since it is a ratio you cannot have a range between 0 and a real number so if you have a maximum recording level of 0dB then an input of 0 the range will be -infinite dB.


This is a simple discussion from the point of view of recording levels.
http://arts.ucsc.edu/EMS/Music/tech_background/TE-06/teces_06.html
 

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