I've had people express concerns about sound levels and put it in context with OSHA standards. So I looked up OSHA standards. The limits are for sound at a continuous level -- like a machine or engine running continuously -- are are are scaled like this: no more than 100 db for 2 hours continuously, no more than 97db for three hours; no more than 95 db for 4 hours. You might approach these limits at a rock concert or outdoor music festival -- but no contra dance I've ever been to approaches OSHA limits. Not even close.
Personally, I have always run sound a little hot (loud) and have had very few complaints. My SOP over the years has been to use my trusty Radio Shack DB meter from the middle of the hall. I use a setting that allows me to measure sound levels for a time -- 10 or 15 seconds usually. After the time elapses, I can check the peak reading and the low reading. I avoid balances during the reading. If I see that the peak reading (not continuous reading) is hitting/exceeding 95 db on my meter, I cut back a little. Overall, I adjust so that we are never going over 95.
That said, I have had people say to me that volume readings should never go about 80db and such. Realizing that db readings are logarithmic (90 db is 10 times louder than 80 db), that just seems much to low to me (and it may be that there's an issue with calibration of the meter??). And by the way, what about your favorite touring band that does it's own sound. Everybody loves it. What levels are they running? Recently we had a big name band that does its own sound pass through and one of my colleagues took readings (we are in fairly close agreement with our meter readings. Spot checks during the waltz showed 99.9 db peak and 92.6 for low.
My sort of conclusions about all this.
It's very subjective, but on the whole, louder music is more exciting and energizing. As a dancer, I want to feel that the band is right in the room with me, not off on the back of a stage somewhere.
We need to listen to complaints/concerns and make an effort to address them appropriately. That might mean reducing volume. It might mean tweaking the EQ in some way. Might mean raising the speakers. The 100 percent wrong thing for a sound tech to do is to behave with arrogance and suggest to the person that "it's your problem." If there's an unhappy dancer, it is our problem. We may not be able to fix it, but it's our problem.
db measuring tools can be very useful and phone-based tools are free. But -- you have to have a reference source to calibrate. Then, if people want to talk about sound levels, you can pull out a measuring tool and have an intelligent discussion.
Thanks for listening.
Ridge