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.....
BigH
Well-known member
abacus said:
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.
Benedict_Arnold said:
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.
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.
Benedict_Arnold said:
Bill,
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:
http://en.wikipedia.org/wiki/Decibel
Sound pressure level, what is 0dBSPL and how it is used, A, B and C weighting:
http://en.wikipedia.org/wiki/Sound_pressure_level#Sound_pressure_level
Subjective loudness measurement, equal loudness curves and the Phon:
http://en.wikipedia.org/wiki/Phon
Good luck.
What a dB is and how to calculate it:
http://en.wikipedia.org/wiki/Decibel
Sound pressure level, what is 0dBSPL and how it is used, A, B and C weighting:
http://en.wikipedia.org/wiki/Sound_pressure_level#Sound_pressure_level
Subjective loudness measurement, equal loudness curves and the Phon:
http://en.wikipedia.org/wiki/Phon
Good luck.
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