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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB: The Classic Live Audio Board => Topic started by: Simon Eves on January 26, 2019, 12:35:58 AM
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I have been reading the various threads on here about SPL and noise ordinance.
Obviously there's no real way to estimate this in advance, but...
Outdoor amphitheater, probably a 50 yard diameter circle overall, ~250 seats, front seats and stage maybe 10' below outer level, then 8' solid wooden fence and trees around.
Residential areas maybe 150 yards away from outer boundary on three sides, with sparse trees along the way in most directions.
City ordinance is 50dBA during show-times, presumably measured at the residence.
I am aware of the math of SPL drop-off with distance and natural obstructions, but I'm struggling to reach any conclusions about the practical limits this set-up would have in terms of a musical theater production with wireless mics and a reinforced band through a PA of appropriate size (as yet undetermined).
Anyone care to take a guess at whether they will be able to run the show at a volume that makes the amplification worth the effort, without going over the ordinance limits at the residences?
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Unfortunately, there's no way to really estimate that in advance. You can do the math based on your starting level and decrease calculated by the inverse square law. But that doesn't take in to account the seating, acoustical barriers, and other ambient noise. Add to that the fact that SPL is cumulative, and if a truck passes by the residence during your show, it will increase the SPL level accordingly, and the neighbor is unlikely to figure that in to their SPL complaints.
You can start by taking some base readings at their residence before your production ever loads in. Chances are that the ambient noise at their house, outdoors is over 50dBA any way.
You can always go to the City Council and petition for a variance during the times of your show. Explaining the common good to the community that it provides, etc...
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I would totally echo Justices comments. In straight line of sight, as a guesstimate you are only going to get about 9db reduction from the amphitheater boundary to the buildings. I think you would be quiet at around 76 dB at the 50 yard (this is the level of a reasonably busy road). As mentioned above, I would expect ambient noise in a quiet street to be around 60dba, so the spec is almost certainly a nonsense.
If the venue has a history of these events without trouble, I would just be mindful of the situation and do your best.
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You said "presumably" in describing where the 50dbA boundary is. That's not specific enough. Find out specifics of the City ordinance before you do anything else. Where is the boundary? Where is the measurement taken? Was it taken all along the fence or only at one spot?
Is there a curfew for shows? Is that 50dbA threshold relevant for all hours or just specific hours?
When was the 50dbA ordinance enacted? Why was it enacted?
What are the consequences for breaking the 50dbA threshold? Is that threshold peak or average? If average, how long is it required to go on before it becomes a violation? Is it a violation if it measures 50dbA at one spot but not another?
What entity owns the amphitheater? Is there a different entity that manages it?
I think you need to know the answers to every one of the above questions before you can attempt to make any case for raising that threshold. There can be a lot of people to convince that the 50dbA threshold is unrealistic. A small, unamplified chorus of singers would easily go past that threshold at the back wall of the seating area.
If there is a government agency involved with the ownership and/or maintenance of the venue then it becomes even more complicated.
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You are never going to get under 50dBA.
But you can be considerate of the neighbours. Letterbox-drop them flyers saying what is happenning and what time of night the music will stop.
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You are never going to get under 50dBA.
But you can be considerate of the neighbours. Letterbox-drop them flyers saying what is happenning and what time of night the music will stop.
And MAKE SURE you stick to the advertised time.... You won't get a second chance.
Chris.
ya, 50dB is unrealisatic.
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Simon, lots of advice so far but we've discussed noise from events a fair bit and IF you can get some Search Love, there was a gold mine of participation a few years ago. I don't trust my memory for the specific suggestions that came from it but...
Get the city ordinance as written. If that's the standard it's published. It's what the production will be obliged to comply with, at least to start the discussions. Make some measurements (play back some recorded dialog and music, maybe?) and observations if you can.
Next, I'd want to find out if there has been recent enforcement (search for municipal court cases with the ordinance number) and what the circumstances were. Figure out who enforces this (police or health dept or?) and what methods and equipment they utilize.
Is there any hope of being mostly compliant? If so, know what you have to do and do it until someone above you says "give me more!" If not likely to be compliant what does research show to be best - play "oops, sorry about that, folks" or be pre-emptive, knowing that raising the issue could derail any permitting or licensing from the City?
There are lots of unexpected "stakeholders" in these kinds of things. You may want the theatre's board members to do some of the sussing out of who else might be involved and what their positions are, and how they might be brought over to support your group.
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Let the local police (or city council, etc) know about the event, and when it will end. Ephasise the nature of the event, eg community musical theatre.
Also bear in mind that the people who live 150 yds from an outdoor amphitheatre are probably quite accustomed to hearing events.
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Let the local police (or city council, etc) know about the event, and when it will end. Ephasise the nature of the event, eg community musical theatre.
Also bear in mind that the people who live 150 yds from an outdoor amphitheatre are probably quite accustomed to hearing events.
That's a great way to have the SPL police show up every night and issue a ticket every time you go over their arbitrary and unrealistic noise level.
You will have to petition the City Council for a variance in the noise ordinance (and hope they approve it), if you want to stay legal.
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City ordinance is 50dBA during show-times, presumably measured at the residence.
Have a look at this chart to see what you're up against, in short if the residents can even discern that there is something going on in the amphitheater then you are in violation.
(http://www.achievehearing.com/images/cdc-decibel-scale-dBA-noise-levels-infographic.jpg)
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Police have better things to do than issue tickets to benign events.
These sort of events must have some sort of tacit city approval; why would they have built an ampitheatre otherwise?
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Police have better things to do than issue tickets to benign events.
No they don’t. Especially when some busy body connected to local political power calls in a complaint every night.
Stay legal, within the letter of the law, or get a variance in the ordinance.
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What type of an area is this outdoor amphitheater in?
Standard urban residential area with normal street noise, is there any major highway or heavily traveled street near by or is it in the middle of a park where all you can hear are the birds singing and the crickets at night.
50dbA is a crazy low number. I going to get my meter and see what the front yard measures at my place, I live in the country but there is moderately heavy traveled state route about 250 years away.
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I didn't want to name names, but whatever... here's the venue:
https://www.google.com/maps/@37.9791563,-122.5180622,545m/data=!3m1!1e3
Google Maps does a pretty good job of displaying that in 3D if you hold down your Ctrl key, even down to the individual trees!
Yes, that's a major freeway ~200 yards to the west, albeit with a fairly substantial concrete wall along it. And a school. And a soccer field. And tennis courts.
I haven't found the actual city paperwork yet, but I am assured by the venue management that it's 50dBA at the residence, dropping to 40dBA after 10:30pm (which is probably about when the show will end, given that it's summer and they don't start until 8:00pm because of the light).
That is clearly ridiculous, and this venue has been in operation for several decades with (I assume!) no issues on this front. I also don't want to cry wolf on them (or to them) unnecessarily. Then again, I don't want them to get shut down when there's a four-week run in the balance.
I am especially twitchy on this subject given the following very related local issue faced by a similar group, although one operating at much smaller scale and absolutely without amplification, which sadly negates one of your assertions that anyone who lives within 150 yards of a venue should expect some noise:
https://www.marinij.com/2019/01/26/mill-valley-neighbors-decry-amphitheater-noise
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I'm going to guess the ambient background never drops below 50dbA in that area.
But the A weighted scale will remove the some of the low end road noise rumble from the measurement.
The interpretation of the measurement and who is doing the interpreting is the wild card you have to deal with.
A few years ago I was doing an all day event that was 90% playback music with some random announcements at a campus facility. About mid way though the day I saw this guy coming over and I could tell he was on a mission saying the music was too loud as he was measuring something like 72 db on his meter (he actually had a meter not a phone app) and was pointing to the spot he measured on a street corner and couple blocks away.
All the while he's measuring in the area where I was set up and was kind of confused as to why he was not getting that much of a higher reading and we were easily talking while the music was playing.
While not part of this event he was part of the facility staff, so we both walk out to the area he first measured and was kind of complaining about. Sure enough his meter was reading about what he said and you could hear some of music faintly at that location.
Then I motioned for them to turn off the music, his meter reading never changed and I knew it wouldn't as the ambient noise was a healthy 75 db at that point and the music level at that location was below that.
For what's worth his meter was on the A weighted scale. I went back later with mine and measured about the same thing.
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I just took some measurements with my phone of the ambient noise at the actual site.
I'm not sure what curve it's using.
Time 7:15 pm.
The primary source of the noise is the freeway on the other side of the houses.
In the amphitheater and stage : 55dB average.
Outside the fence in the parking lot : 60 dB.
Across the playing field at the residential street : 70dB.
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I just took some measurements with my phone of the ambient noise at the actual site.
I'm not sure what curve it's using.
Time 7:15 pm.
The primary source of the noise is the freeway on the other side of the houses.
In the amphitheater and stage : 55dB average.
Outside the fence in the parking lot : 60 dB.
Across the playing field at the residential street : 70dB.
As it is uncalibrated the figures from your phone will innacurate, however, they strike me as the sort of figures I would typically expect in those sort of areas. What is interesting, is that they show a 15db (whatever weighting), reduction in level between the street and the venue. There appears to be a wall and two tree lines between the venue and the street, so that appears to be reasonable. If you worked from 76db arbthe back “wall” of the venue, you probably would be realistically around 60db at the street. With average traffic noise I think you would have little chance of hearing anything. That being said, my local council got a noise complaint about an event, even though it had been cancelled! People that complain on these events are sometimes complainers by nature. Good luck!
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If you worked from 76db at the back “wall” of the venue, you probably would be realistically around 60db at the street. With average traffic noise I think you would have little chance of hearing anything.
Sounds plausible. Thanks, everyone!
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As it is uncalibrated the figures from your phone will innacurate, however, they strike me as the sort of figures I would typically expect in those sort of areas. What is interesting, is that they show a 15db (whatever weighting), reduction in level between the street and the venue. There appears to be a wall and two tree lines between the venue and the street, so that appears to be reasonable. If you worked from 76db arbthe back “wall” of the venue, you probably would be realistically around 60db at the street. With average traffic noise I think you would have little chance of hearing anything. That being said, my local council got a noise complaint about an event, even though it had been cancelled! People that complain on these events are sometimes complainers by nature. Good luck!
My phone is pretty close to my SMAART rig with a calibrated mic on C weighting.