A decibel is a scientific reference as to how loud something is. Unless you are doing a tech paper, it’s a non-starter for most sound-loudness descriptions because it’s tech nature doesn’t stick the landing.

“That was the loudest show I’ve ever heard!” This is fine for most writting.
vs
“That show was way over 100 decibels!” No one knows what this means, therefore, it will either cause them to igore it, lessening the impact of your writting, or you will have made them feel stupid and they’ll move along and forget you.

Octave, on the other hand, is a description of the +/-8 state of something, but also tell the reader that thing being described is much higher, or lower, than the thing it’s being compared to.

For example, “This car clearly sings an octave higher than it’s competitors.”, meaning the motor really screams. Or maybe, “His impulses reside in the lowest octave of human desires.”, meaning he is a degenerate.

Cheers

Dar

Hmm…that’s a low value; there has been a fair amount of variation, but the usual standard value nowadays is 261Hz and some change (so the A above middle C is 440Hz).

Each 10dB decibels) corresponds to multiplying by 10 ( or dividing by 10).

And if something is 100Billion times smaller then we say it is
-`140dB ( ie, minus 140dB).

The formula is 10 LOG of the ratio.
If the ratio is 100Billion = 100,000,000,000 then the LOG of 100,000,000,000 is 14.
then you multiply the 14 by 10 to get deciBels.

(Note: LOG means logarithm. On your calculator, to get the ratio 1000 in dbs, press the LOG button then enter 1000 and then press ENTER. Then multiply that answer by 10 to get dbs)

It is easier to say 140 dB than to say 10,000,000,000.

Now OCTAVE:
As far as octave is concerned. An octave is a frequency ratio of 2 to 1. Middle C is 256 cycles per second. The C above that ( 7 notes higher) there are 8 notes to a musical scale, CDEFGABC`.
C` has two times the frequency than C. Frequency means how many vibrations per second.

for instance—the first 2 notes of the song “Somewhere over the rainbow” are an octave. Sing it. Some-where = C, C` or 256 vibrations per second and 512 vibrations per second. 9assuming you start on C)

In engineering we also use the term “octave” to mean that a frequency is twice as high as another frequency. 105 on the AM dial is on octave hight than 55 on the AM dial.

I hope this cleared it up a bit. I am a musicialn and an engineer
—so I deal with dBs and octaves every day.

Actually, no. First, the decibel isn’t an absolute measure; like an “octave”, it only measures the difference between two levels (in the case of acoustics, of pressure) — when you say a vacuum cleaner is “70dB”, it’s lazy language, understood to mean 70dB louder than some mutually-understood reference – usually, but not always, 20 micropascals. Second, it often/usually isn’t independent of pitch: some model of the human ear’s frequency response is applied to try account for the way we perceive loudness relative to frequency (you’ll see units like “dBA”, and occasionally other letters; “A” is the name of a particular common frequency weighting…most of the time when people talk about “decibels” in sound, they really mean dBA)

Octave describes a relationship between two notes of different pitch, or frequency. Specifically, of a pair of tones which are an octave apart, the higher has twice the frequency of the lower. “Octave” is not a unit of measure, although frequency is. (The division of an octave into 8 notes or tones is a part of culture not dictated by any physical property).

Decibel is a unit of measure which applies to the amplitude (loudness) of sound, independent of its pitch. Note (pun intended) that a sound of any given pitch can be either loud or soft (lots of decibels or few), and a sound at any specific decibel level can be high, low, or multi-pitched.

Lovers of music and English will appreciate the distinction.