A question about dynamic range

[BrianT]

What is the widest imaginable dynamic range the ear could be meaningfully and practically subjected to in the real world?

Obviously, volume just below that causing permanent deafness vs the self noise of the human body in an anechoic chamber is the extreme, I would suppose. Fascinating, but hardly a practical scenario, even disregarding the ringing in the ears from the loudness obfuscating the quietness. OK, I'm getting too complicated with the question.

So I'd appreciate opinions on the max dynamic audio range that could realistically matter. Anyone care to venture a guess?


Regards.
Brian T

[Dave Martin]

There was some discussion somewhere or other about the highest level that can exist in air (the Shuttle hits it on take off, and so does a thermonuclear explosion). Above a certain level, air simply can't compress and rarefy any more. For some reason, I'm thinking that it was around 180dB. and it seems like about 20dB is is as low as most people can hear in a quiet room. There's your total dynamic range. Of course, I belive that immediate damage to the human ear occurs around 140dB. and most rooms where people live don't have a noise floor as low as 20dB.

And all of this may be wrong - I haven't had a bunch opf coffee today.

By the way, BT - are you going to the AES party tonight at Paragon?

[ExistanceMusic]

The dB scale itself is based on the dynamic range of the human ear, the quietest potential sound a human with perfect hearing (IE a baby- or those with the so called "golden ears") can recognise being 0dBspl.
The upper limit varies, but the commonly accepted "threshhold of pain" is 118dB, although I have a feeling that this was measured at 1K, beacause I've heard lower frequencies at over 135dB, and although not comfortable, not painfull.

Thats the medically/scientifically accepted range, but I think Dave's answer pertains more to your question, because we all know the real world is NOTHING like test conditions. Hope this helps though .

Oh, BTW Dave, I'm pretty sure the apsolute upper limit must be more than 180dB, as the current world SPL record for Car Audio ( , my other secret passion comes out...) is currently 175dB, and amp, vehicle, speaker and enclosure design are far from perfect as yet, so I'm sure we'll see 180dB before too long!

http://www.mtxaudio.com/caraudio/rou...d/holland4.cfm

[fishtop_records]

In addition to the top of the range numbers, we
need to think about the low end as well.

I don't know what your "human in a anechoic chamber"
measures out to, but normal quiet living rooms are
about 50dB and studios spend lots of money to
get the residual noise (traffic, A/C, xerox machines
upstairs, etc.) down into the 30s.

So if the bottom is 30 and the top is 120,
then we only need 90 dB, and a CD
will deliver all the range we need.

While I don't belive that 16 bits is enough,
I'm sure that the designing engineers considered
that as both sufficient for real world, and
fits nicely into two bytes of a computer.

[Jay Kahrs]

Real world? Probably about 70dBspl. In the audio world, both studio and live sound I don't ever think I've had a swing bigger then 25dB.

[Ted Nightshade]

I know a guy who likes to fantasize about softly rubbing his shirt sleeve and then detonating a cannon just to experience the maximum he can imagine in dynamic range, real world.

We can hear a lot of stuff 20+ dB down under the ambient room noise, I'd take that into account.

I'm thinking much, much more than 100 dB. Live percussion with good dynamics would easily accomplish that, from the final fading zing of a triangle to the next sharp transient.

"In the audio world, both studio and live sound I don't ever think I've had a swing bigger then 25dB."

Unbelievable. If the meters on this HEDD are anything to judge by, and of course they just measure peak, 40-50 dB swings happen often enough around here. Mmmm...

[Jay Kahrs]

Originally posted by Ted Nightshade
"In the audio world, both studio and live sound I don't ever think I've had a swing bigger then 25dB."

Unbelievable. If the meters on this HEDD are anything to judge by, and of course they just measure peak, 40-50 dB swings happen often enough around here. Mmmm...

You mean to tell me that if your in a club and a band is playing you've had dynamic range swings bigger then 20-25dB? Doubt it. The average place I do FOH at has a noise floor (people talking and background music) of roughly 80-90dB SPL, the band usually hits about 110dB SPL at the stage.

Same thing in the studio, once a song has started I've never had a mix with over a 25dB swing. Maybe once or twice in 7 years but not as a hard fast rule. If I was doing lots of classical it might be different, but for any kind of "pop" music it never happens. At least not to me.

[Ted Nightshade]

Played a show last week, we had 400 people just about dead silent during the quiet part, and man was that part quiet, about as quiet as you could possibly strum an acoustic guitar, until the vocal came in full on, and that's loud. Give ya chills, it does. A little later in the tune, all hell is breaking loose, but in a nice way. Major vibes transients, hooboy they're hot.




I see what you mean though, how the loud room ambience would often eat up all the dynamic range on the quiet side, and yes most times it does.

In the studio of course, or in a classical concert hall, there's not so much of that room noise. I've attended a La Mer conducted by Michael Tilson Thomas that had you straining your ears one minute and plastered against the back wall the next. When the bass drum went off loud, I looked over at the seats on the other side, full expecting to see a smoking ruin where someone had bombed the symphony hall. No kidding. That was loud, and sudden. That's dynamics!