dB-A or dB-C?

[Bama214]

I've been following several threads here related to loudness listening levels. Many (if not all ) posters express their opinions in "dB" without clarifing whether they mean dB-A (usually used for things like OSHA safety levels) or dB-C (which includes more of the frequency band). Is there a de facto assumption here that "dB" means dB-C?

 

[sergeauckland]

I'm more inclined to the view that in the absence of a qualification, it's more likely to be dBA than dBC.
Loudness, as in subjective loudness, is usually expressed in dBA, and for the purposes of Health & Safety, noise exposure is also expressed in dBA.
Amplifier noise specs are most often expressed in dBA, as these will give a better looking number than unweighted or dBC which is close to unweighted.

S.

 

[gnarly]

I vote neither A or C.... they cause nothing but confusion and obfuscation imo
Unweighted dB-Z is all i'll use anymore

 

[egellings]

Is the difference in those dB scales just the reference level they use for their 0dB mark?

 

[sergeauckland]

Is the difference in those dB scales just the reference level they use for their 0dB mark?

No, the difference is the frequency response of the two weightings.

dBA allows for the changing sensitivity of our hearing, dBC is much flatter.

S

 

[egellings]

No, the difference is the frequency response of the two weightings.

View attachment 271668

dBA allows for the changing sensitivity of our hearing, dBC is much flatter.

S

Thank you for the info.

 

[DVDdoug]

I vote neither A or C.... they cause nothing but confusion and obfuscation imo
Unweighted dB-Z is all i'll use anymore

For frequency response you want flat but for loudness or safety/regulatory purposes you need A-weighting.

 

[gnarly]

For frequency response you want flat but for loudness or safety/regulatory purposes you need A-weighting.

Yep. But i don't get the feeling the OP is involved is safety/regulatory sound checking, huh?

Personally, I've found from making many SPL measurements (both for home and live sound), i prefer Z over weighted, for subjective home audio loudness assessments.
I really can't see much of a use for weighted in home audio.

 

[Philbo King]

dBA : How quickly will I go deaf?
dBZ : Is the FR flat?

 

[JeffGB]

As I understand it, for hearing protection you should only use unweighted measurements. The weightings are designed to compensate for human hearing at various volumes but our ears don't care how we perceive the volume, they are damaged by a certain sound pressure level. Just because we perceive a certain frequency more or less makes no difference to the level damage occurs at.

 

[sam_adams]

dbZ. Because Z is twenty-three better than C.

 

[Bama214]

I appreciate all the replies here.

in the main, my post was to raise awareness that simply using the unit “dB” in the various posts I read here (and elsewhere) without qualifying whether it’s dBA, dBC or dBZ can lead to confusion.

As other posters mentioned, I would reference dBA for safety related measures, but dBC when I’m adjusting my stereo or home theater performance.

As an example, I assume that the THX reference level of 85 dB and the Audyssey calibration level of 75dB are dBC measures, but I’m confused when posts reference these levels to ear safety. Adding to the confusion is the term dB SPL, which is referenced to the threshold of human hearing (and I assume to be unweighted).

If only the world was simpler….

 

[Head_Unit]

my post was to raise awareness that simply using the unit “dB” in the various posts I read here (and elsewhere) without qualifying whether it’s dBA, dBC or dBZ can lead to confusion.

I believe most posts have no idea about that. Aren't they often the "is my AVR clipping"/"do I need an external amp" type of threads? Based on a speakers specified and probably exaggerated sensitivity?