Reducing off site bass

citizensc wrote: we did get two noise complaints. What kind of measures have you guys uses?

rohypnol.

snowflake wrote: toastyghost wrote: The AES paper on event noise management is open access, by the way: https://www.aes.org/technical/documents/AESTD1007_1_20_05.pdf interesting discussion of meteorological effects at p.69 if one of your problem neighbours happens to be a at a distance where atmospheric refraction is directing sound it would be useful to be able to create a cancellation in the vertical pattern from your stack and point the null at the problematic angle. I you create a vertical stack (perhaps about 3m) with some of the boxes at the bottom rear-firing and phase inverted, could you not then steer the vertical pattern with delay? Might be hard to predict - but if you found you suddenly had a problem half a mile away due to changing weather conditions you could try varying the delay and see if the problem goes away again. Wish I had the equipment and space to test this out but it's just an idea...

In principle yes, but it’s not typically the bass that causes that refraction issue. Additionally you need to consider the mirror image sources in the infinite baffle space of the ground, which is more complex than you think:
https://www.merlijnvanveen.nl/en/study-hall/135-which-sub-to-reverse
https://www.merlijnvanveen.nl/en/nl/studiezaal/137-which-sub-to-reverse-pt-2

However this is yet another area where actual research and testing ‘out in a field’ is needed. I really wanted to try and work on some of the things in this report for my dissertation, but the uncertainty of COVID regulations over summer time meant I had to choose something safer to focus on back at the start of the year 🥲

More of an issue is the low mid and vocal region. A major problem with big banana hangs of line array is the massive rear lobe that comes off the system straight into the sky; it’s a huge reason behind the focus on passive or active cardioid designs in modern line array systems like d&b’s GSL/KSL, Fulcrum’s FL283, and the use of flown subs behind the main hangs.

That doesn’t help address things out front though. Meteorological factors are logged with mappings by the good types of noise management teams, but I’m not sure how much of that is fed back into research - let alone how much of the data is viable given the lack of controls.

There’s more info on the very complex Nord2000 noise model here:
https://eng.mst.dk/air-noise-waste/noise/traffic-noise/nord2000-nordic-noise-prediction-method/
https://forcetechnology.com/en/innovation/completed-projects/nord2000-noise-calculation-method-auralisation

Edited by toastyghost - 21 September 2021 at 11:09am

martinsson wrote: Abit crazy perhaps, but has anyone on here tested any active solution? For example a bunch of standard 218 boxes, each fitted with a primitive x-over, a mic and a power amp. The idea has been tested for improvement of room acoustics, a box producing a level matched inverse of the ambient lf, could something similar be used for off site lf suppression in a half space environment? Just a thought.

Yes. Some examples are in the AES document, and Rocket Science in Switzerland are the front runners in a system that reacts fast enough. A friend of mine is doing a thesis on it from January.

It’s a lot harder than you think, and has its own issues in the world of perception and psycho acoustics.