Originally Posted by antoniobiz1
If a very quiet room has a 20db SPL noise floor, and a 120db spl is the threshold of pain (and instant hearing damage can occour), how can you benefit from a higher than 96db dynamic range? Do you listen to your drums recordings at 130db SPL?
A quick note on room SPL. Those single digit numbers are of no value in determining audibility. For that, you need the spectrum of that noise and then compare it to our hearing thresholds. I wrote an article on true dynamic range of rooms
which explains this. Here is a referenced graph showing spectrum of admittedly very quiet rooms:
Notice how the room noise dips down to threshold of hearing which is actually negative SPL (!) while the same room has 40 db of noise at low frequencies. It is a fortunate thing that even though low frequency noise is very hard to block, it is also landing where our hearing sensitivity is the lowest.
Here is another graph referenced from my article on spectrum of home listening spaces:
We see that the best room ("min") has noise that is well below threshold of hearing at 1-3 KHz. Even the "average" of the rooms has a noise level of 5 dbSPL at 6 Khz.
Put more simply, we need the resolution and dynamic range to represent the spectrum of frequencies that we hear the best. It doesn't matter if we don't need it in low frequencies or high where our dynamic range is lower.
There are also other factors that invalidate using room noise as the floor. Listening tests show that if you have constant omnidirectional noise in the room as would be the case in ambient room noise you can detect noise coming out of a specific source, i.e one of your speakers. The cognitive part of hearing determines that the constant noise is not of significant value and attenuates it. But noise coming from a specific direction is detected. Think of evolutionary need to hear the noise from a threat in presence of environmental noise.
Also, we are able to hear "through the noise." So even if the noise floor was this high, it would not cap what real tones/music we could hear below it.
So all in all, this is much more complicated than taking single figure numbers for room noise and using that to determine our dynamic range. We can show that our hearing has 120 db SPL of dynamic range which represents 20 bits of resolution.