i heard someone describing the level of a sound by saying its 30db

i'm kinda confused by this expression as daw usually works towards 0DB

so when u say a sound is as loud as 30db how should i understand this in relevance to that we work towards reaching 0db in the daw

 

You should understand that someone telling you something is 30dB is not talking about your DAW. You can lookup many different style charts of these "observations". They are generally referring to dB SPL, which is sound pressure level.
https://www.protoolreviews.com/understanding-sound-pressure-level-spl-decibel-scale-db/

But it can refer to any of the other calculations and measurements, when referred to inspecifically.:

Here they are:

• dBSPL: 0dBSPL = 20μPa, or 20 Micro Pascal. Pascal is the international unit of measurement for sound pressure.
• dBu: 0dBu = 0,775V, or 0,775 Volts. ...
• dBv: 0dBv = 1V. ...
• dBVU: It varies because it is not standardized. ...
• dBFS: 0dBFS means that all bits are being used. ...
• dBW: 0dB = 1W, or 1 Watt.

as example from google:


What does 40 dB sound like?

Noise Source Decibel Level comment
Library, bird calls (44 dB); lowest limit of urban ambient sound 40 One-eighth as loud as 70 dB.
Quiet rural area 30 One-sixteenth as loud as 70 dB. Very Quiet
Whisper, rustling leaves 20
Breathing 10 Barely audible

 

Last edited: Jul 21, 2022

DAW is dbFS. https://en.wikipedia.org/wiki/DBFS

db is dbSPL https://en.wikipedia.org/wiki/Sound_pressure#Sound_pressure_level

 

decibels are a way to measure against a reference, which is "set" at 0dB. That reference though could be anything really (even chemistry related stuff), that's why you usually see "dB" accompanied by something else (dBSPL, dBu, dBFS) which tells you what is it refering to.

When talking about dBFS for example, 0dB is the highest possible value on a digital system, it's a maximum, so what you normally see are negative values.

dBSPL take as reference 20uPa (that's pressure of a physical thing like air, so nothing to do with daws), which is roughly the minimum ammount of sound pressure required for sound to be audible, and since this is mostly used for things you can hear, it tends to take values well above that minimum, so above 0dB.

Now, since you heard 30dB, it's very likely they were talking about sound in the air, so 30dB SPL (or one of it's variants)

 

"30dB" relative to what? Which kind of dB? As said above, there are several ways and cotexts in which "dB" may be used, and they are very different between them.

"30dB", said like that, doesn't mean anything. It's like saying "one meter". What is it? Width, length, heigth, depth, less than, more than...?