Ok I know I can test this with a meter and I will next Saturday.
Until then let me ask this, At dance level (loud but not killing peoples ears) what would would be the db?
How loud is 89db with recorded music with a double Pas system?

These are examples of 90 dB as described on the following sites. 89 dB is going to be very close.

How loud is loud
Heavy truck @ 15m
Busy city street
passing motorcycle
Lawn mower
Loud shout
Sreaming child


Noise Center: Decibel Levels
- tractor, truck, shouted conversation

Noise Levels
- motorcyle at 25 feet

And Mike,
Since you have the wisdom to be exploring this try:

H.E.A.R. | Hearing Education and Awareness for Rockers

And from the same site
Decibel Trivia

And finally

Speak (walk, play) softly and carry a big stick

What a relief to finally understand what Mark-at-Bose is doing here.

I found this on the H.E.A.R site and found it alarming! I do not know of many gigs I have done where I would have passed the test.
Soundcheck

quote:

Here's an easy, safe and effective way for musicians and fans to check to make sure loud concerts aren't hurting your ears.

Before the show, set the volume of your car radio to a level where you can barely hear the words. A talk show works best, as sometimes it is hard to understand lyrics in music. After the concert, turn on the radio to the same setting.

Can you still hear and understand the words? If not, you're experiencing a form of short term hearing loss called temporary threshold shift. When this happens too many times, the damage can become permanent.

Mark, I went on that website and found that information very interesting. Next time (two weeks from now) I have a DJ gig, I will try that test to see if I can hear it. Although, I don't think that will be a problem with the PAS, as it was with my EV's.

Let me give some real (mobile DJ) world figures to help answer Mikes question.

I use a sound level meter (Radio Shack digital type) at functions to monitor sound level. These are the kind of levels I run at.

85-90dB is typical at a weddings and family parties.

90-95dB is typical at youth orientated events (such as 18th Birthday parties).

Corporate events can be anywhere from eighty to almost a hundred dB, depending on the age group and kind of event.

I have occasionally reached 100dB (repeatedly asked to turn it up) and that is just stupid - far to loud. (However you can experience this kind of level in quite a few night clubs.) At these levels, my ear plugs go in.

Above levels are with the meter fixed to the front of my console level with the fronts of my speakers (802's). Figures measured on the dance floor are similar or higher (1-5dB).

I use the following settings:
Response: Slow - to get an average volume, rather than a peak.
Weighting: A - this approximates the ears response by being more sensitive to mid range (therefore less sensitive to bass). Many people use C weighting, and it gives a higher dB level on full range music, but A weighting seams to give a better reading of how loud a sound is perceived to be.

This message has been edited. Last edited by: RobbieD,

Unfortunately perceived loudness is a very complicated phenomenon and it is quite difficult to squeeze it into a single number.
dbSPL is most often used for legal purposes but it needs proper configuration. A professional sound pressure level meter has hundreds of settings.

In my personal opinion "C" weighting is more appropriate for sound levels above 80 dB. The reason for the different weighting is that the ear's frequency sensitivity changes with level. This can be represented by the so-called "equal loudness curves", as show for example here http://hyperphysics.phy-astr.gsu.edu/hbase/sound/eqloud.html#c1

The "A" curve is based on the frequency sensitivity at around 40 phone whereas and the "C" curve closer to the human frequency sensitivy at 85 phone. So for typical live music sound levels "C" should be a little closer to perceived loudness.

But then again, that's just one part of a very complicated puzzle. It's fairly easy to construct two sounds that have the same A weighted sound pressure level but significantly different loudness.

quote:

Originally posted by Hilmar-at-Bose:
The "A" curve is based on the frequency sensitivity at around 40 phone whereas and the "C" curve closer to the human frequency sensitivy at 85 phone. So for typical live music sound levels "C" should be a little closer to perceived loudness.

Thanks Hilmar. I think I shall start using both.

If I play a current R&B track with lots of bass, and then a 1950's rock and roll track with little bass at "the same volume" then "A" weighting gives me a similar reading for both tracks.

But quite clearly the newer track is more "powerful" due to the chest thumping bass, and I find "C" weighted readings show a massive difference.

However, in the above comparison, would the extra bass of the new track potentally cause more hearing damage, even though the newer track proberbly has a slightly lower midrange volume?

I'm really not an expert on medical issues, so it's really hard for me to give reliable information here.

As far as I know most noise related hearing damage is caused by mechanically damaging the nerve cells in the cochlea. Different frequencies map to different nerve cells, so the exact location of the damage will shift with frequency content but my guess is there will still be damage nevertheless at that level.

Another thing to consider here is that passive hearing protection (ear-plugs) are much less efficent at low frequencies, i.e. even people that are careful enough to wear hearing protection, excessive bass poses a risk.

quote:

Originally posted by Hilmar-at-Bose:
I'm really not an expert on medical issues, so it's really hard for me to give reliable information here.

Me neither, but, as usual, there are lots of interesting grey areas.

The literature so far reveals that:

Noise you like (music) is much less deleterious to hearing than noise you don't like (jack hammers).

Harmonically related noise (music) is much less deleterious to hearing than random noise (jet taking off).

This is why Pete Townshend's hearing lasted as long as it did compared to, say, WWII pilots' hearing. Just where a band such as Napalm Death fits on these continua is open to discussion.

Also, low frequency content does not seem to be as serious as high frequency content. Maybe it's as simple as in the octave between 30 Hz and 60 Hz there are 30 frequencies (sorta, kinda) and in the octave between 3000 Hz and 6000 Hz there are 3000 frequencies (sorta, kinda). From personal experience, I can suggest that 95 dB of bass guitar is easy to take, whereas 95 dB of tin whistle is instant ear plug territory, even though you would judge them to be equally loud.

None of this stuff has any useable metrics attached to it, and may never. Caveat auscultator.

Mike

PS Right on on the C weighting, Hilmar. I highly recommend everyone in this business have two technical goodies: one of those plugs with LEDs on them that tell you that electrical outlets are in good condition (it's amazing how many are not), and a Radio Shack SPL meter. Accurate enough for our purposes, and very informative.