It was a Music For Youth festival with a relatively small audience in a school concert hall with the audience keeping respectfully quiet. Not some boozy Glastonbury type festival with thousands of people yakking their head offs.
Dynamic range is a a somewhat moveable target, in the hi-fi world at least. I chose a 60dB range for various reasons, not least because it gives an indication of what is possible, rather than what is normal.
A well recorded solo piano can easily be recorded with that kind of dynamic range, which is why most hi-fi systems fail to reproduce this instrument with any degree of authenticity. 60db dynamic range was also chosen because it is about the maximum range possible for even the best system.
Even in a 'quiet' room, background noise is going to be around 40 - 50dB, so a 60dB range is going to peak at around 100 - 110db, probably too loud for any domestic situation unless these peaks are of extremely short duration, which they can be if we are talking about acoustic instruments rather than their electric counterparts.
Well recorded acoustic music can display a very wide dynamic range even though it is still compressed to make it's playback on radio or modest audio systems practical, it still achieves a far wider range than pretty much anything involving electric instruments.
Confusing these capabilities with the realities of commercial recordings is a somewhat different argument. Even top quality broadcast media, Radio 3, for example, limit their dynamic range, often quite drastically, and most pop recordings use as much compression as they can get away with, as you say, loudness is every thing but this does not mean that wide dynamic range material does not exist.
We do so many shows in a row,
And these towns all look the same,
We just pass the time in our hotel room
And wander 'round backstage,
Till the lights come up, and we hear that crowd,
And we remember why we came.
A room away from traffic noise and not under aircraft flight paths on a still dry day or evening with the central heating off and the rest of the family away or asleep should have a background noise level of around 30dbs. Or a quadruple glazed room with thick walls and a thick door in a calm house should have the same background noise level.
Plus it's possible to hear sounds that are below the background noise level, especially if they are at a different frequency.
You need a mind boggling small amount of power to produce noise at 30dbs compared to 100dbs. If you need 10 watts for 100dbs, you need one millionth of a watt at 30dbs. This also has implications for distortion levels on the recording format for analogue and digital sources. Analog tends to distort more as the recording level increases. Digital tends to distort more as the recording level decreases.
To put that into perspective, if we were to draw a straight, non-logarithmic, graph of powers for given sound levels and if we chose a scale where 1mm represented the watts required for 30dbs, then we'd need graph paper higher than Mount Everest to show the watts required for 100dbs.
The loudest noise on the planet is, without doubt, the screaming two year old in the seat row behind you as the 747 descends andthe child's ears begin to pop.....
Or don't pop!
The ear processes sound in a logarithmic form not a linear form, therefore volume doubling requires 10 times the power (10db), compared to 2 times the power if it was in a linear form.
1w = 50db
10w = 60db
100w = 70db
1000w = 80db
Each 10db is a doubling of volume.
If memory serves me right, the formula for gain in decibels is:
Gain = -20 x ln(A/B)
ln = natural or Napierian logarythm (to the base e = 2.78128 - not to the base 10)
A is the output and B is the input
SO it transpires that an increase in "loudness" of just over 3 decibels represents a doubling in "loudness".
I had to explain this to a safety manager who, in a new building a company I used to work for moved into, got a decibel meter and measured the over-loud fire alarms and found out they measured "only" 3 decibels above the OSHA noise limit for an industrial workplace, let alone an office.
Based on my experiences of Health & Safety managers, that's no surprise whatsoever.
Some time ago in Ken Livingstones Peoples Republic, the authorities tried to bring in a limit on the sound level at live gigs.
One evening, at a famous pub on the Fulham Palace Road, we had a health and safety chap set up a system that would automatically cut power to the stage area when the maximum allowable SPL was exceeded. I was chatting to him while setting up the front of house desk, on stage the drummer was setting up his kit. After going through his setup routine the drummer launched into a practice solo and all the stage lights and power was immediately shut off.
See, said the health and safety guy pointing at the desk, you had it up too loud. Really I said, holding up a unconnected power lead, at that point neither the desk nor the PA were even plugged in, let alone powered up.
Live music is loud and extremely dynamic and a failure to come even close to replicating these dynamics is the major failing of most hi-fi systems.
I am afraid your memory does not serve you right. It is log (to the base 10).
For those interested in understanding dB, sound pressure, and perceived loudness, I can recommend the excellent services of Wikipedia. While it is a bit flaky in certain areas, generally for basic technical information like this it is very good. It is certainly more reliable than reading the posts in this thread.
What a dB is and how to calculate it:
Sound pressure level, what is 0dBSPL and how it is used, A, B and C weighting:
Subjective loudness measurement, equal loudness curves and the Phon:
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