Local Venue With A Noise Problem!

[Sound In Gloucestershire]

A local Nightclub has asked my opinion on a problem they have, I said id go away and ask the Genius's on here! (Geni?)

 

Over the last week, theyve been getting alot of noise complaints from a nearby block of flats, of course the weather was blamed, as everyone has their windows open! However Environmental health attended on Monday, took noise measurements outside the venue and were satisfied with the noise levels. However they were then called into the complainants Flat which is quite some distance away and it wasnt Volume, it was bass! They ran the rest of the night with all subs off (awful sound, but meant they were allowed to stay open!). My suggestion was that we could possibly eliminate some of the "problem frequencies" through EQ, whilst still having some bass!

 

So my question is, does anyone have any suggestions as to what Frequencies might be causing the problem? Or if there is a way of measuring this, short of trial and error? They play club style music, mainly Rnb and dance, no dubstep or dnb nights

 

Thanks in advance!

[Shez]

The last time I did noise measurement at a festival, measurements were taken at the property boundaries - windows open or not wasn't relevant. Measurements were taken with a decent portable spectrum analyser but using ears also. Sub levels that showed within limits on the analyser could still be deemed to be too high by judgement call if it was the type that could rattle windows. Making the call that the headliners were too loud wasn't the most fun decision I've had to make.

 

A smartphone spectrum analyser might give you some idea of problem frequencies though they're not particularly accurate. A good ear is more useful. I suspect you'll be looking at around 40-80Hz - the kind of frequencies that you can feel on a dancefloor and that DJs love because of that... They of course are also the sounds that are the most difficult to contain within a building.

[Brian]

...does anyone have any suggestions as to what Frequencies might be causing the problem? Or if there is a way of measuring this, short of trial and error?

 

I suspect that they are hitting a resonant frequency somewhere in the flats construction.

 

Which means it's impossible to guess or even realistically calculate it. So, I think, it's going to be down to trial and error and seeing what frequencies kick things off.

 

What controller do they have feeding the subs?

 

Could you get away with feeding them Bose 302 style? ie lots of 120Hz and not a lot else?

[Jivemaster]

What changes have been made recently to the club? Changed or moved the bins could change the bass sent out of the building. Was there a time "before complaints" can they revert to that set-up.

 

Have they time to do a precision study of the resonating couple of club and flat and see whether some really sharp notches could ne applied to the bass so that the resonance doesn't happen.

 

It's possibly a feature of the moisture content of the earth which will change with autumn rains.

 

Can the club afford to buy the flat and let it to staff?

[Oldradiohand]

You could try asking what frequency was causing the trouble and notching it out but exciting standing waves in other peoples' properties is a difficult one. It would be interesting to know what measurement method was used and to what criteria it was compared. From my experience of council workers and noise measurements many don't know one end of a noise meter from another....

[Sound In Gloucestershire]

thanks for the replies so far guys

 

The police and Environmental health were satisfied with the noise levels outside the club, but even the management of the club agreed that the noise within the flat was unacceptable, no meter required, the bass was noticeable

 

There have been no changes to the sound system or EQ in a long long time, there were noise problems last year which were sorted out with about 10k worth of sound proofing, so its quit a surprise to suddenly get noise complaints again

 

Without getting scientific my first thought was also to just cut all bass below 80hz, I think we'll just have to give that a go and test the water somewhat!

[Matt Riley]

Why not read up on cardiod sub arrays, and see if you can experiment with these to keep the sound away from the troublespot?

[kerry davies]

Quite. I had an instance of the ground floor of a nurses home unable to hear a whisper while the upstairs windows were falling out some three miles from the gig. It was because I had set up four sets of speakers on the corners of a dancefloor to cut down levels and created a 6-7m/approx 50Hz wavelength bouncing across open fields.

 

The frequencies will be below 150Hz otherwise you would get more general and measurable "noise". It will usually be within 10-20Hz which can be "notched" out.

 

Try an experiment first off. Walk away from the club and see if you can hear the intervals at which the bass is most noticeable. Take that measurement in metres (big steps!) and divide 343 by that distance. That will give you an estimate of the frequency in Hz and notch there.

 

So if the bass rises at 7 metre intervals; 343/7 = cut 50Hz. At 5 metre intervals; 343/5 = cut 70Hz. Etc. Might work well enough to give a rough guide without cutting everything. No promises.

[S&L]

I do a reasonable amount of this sort of thing with my day job...here is my two pence worth:

as the law stands the EHO is allowed to insist on levels no greater than the background noise levels. The EHO is usually very approachable. if the job landed on my desk, here is how I would deal with it:

1. work out a possible proposal for compliance.

2. contact the EHO, explain what a likely solution may be and explain that this will need a full acoustic survey.

3. hire a decent meter to measure each of the major frequencies - and in some cases a meter that will measure in narrow bands around the likely frequency problem.

4. take measurement with and without the nuisance at the nearest point that is likely to complain. sometimes you can gain access to a likely complainant property with the windows open (the EHO wilo usually negotiate this and accompany you if there may be any 'people' issues. windows shut won't do but an agreed point close to the complainant, outdoors may be acceptable You would be amazed how much background noise there is from traffic etc that may already partially mask the issue. BUT the measurements need to take place at a similar time as the noise is active. so you cant take readings that give day time traffic masking and apply that to a night time problem - unless the night time traffic is similar (I have found this in one case previously).

5. you then have two sets of readings and therefore two sound graphs you can overlay on each other - by doing so you can see the resulting noise drop you need at given frequencies. from this you can develop an action plan. and the EHO will give a reasonable time to run calcs and consider options. topography (man-made canyon's etc) may mitigate or accentuate the levels.

6. at this point you have only two options, either to remove the troublesome frequencies or contain them. it's worth looking at leaky sound paths at this point. open vents, extract ductwork, poor construction details, open doors and windows at the venue etc. often a loud nightclub/pub can be contained by looking at those leakage points. obviously there are other possibilities, as discussed above - but consider all sorts of things - a maintenance change of extract vent on one bar I looked at several years ago allowed a leakage path which made things much worse and was eliminated once corrected.

there are 3 take home messages:

1. once the EHO are involved the issue isn''t going away until solved.

2. EHO's are approachable,

3. there is no substitute for good accurate data. a wrong guess will aggravate the complainant and cause the EHO to lose faith. better to have good data and be sure.

[Jivemaster]

If the club and the complainant are well established, but the complaint is new, go back and look for what changed to cause complaints. -Hot weather doors open, even inside are the most obvious, Vents, air-con filters, kitchen fume extract all come to mind as possible places where changes like a different brand of filter could have an audio leak.

Are you sure that the bass comes from the club? Could there be a recent tenant in the block with a sound system -check on nights when you know the club PA is OFF.

[jamesperrett]

However they were then called into the complainants Flat which is quite some distance away and it wasnt Volume, it was bass!

 

It could well be that your subs are putting out frequencies more suited to a geological survey than music and they're doing exactly what is expected, bouncing off the bedrock and up into a ground based structure a little way away. If you can gain access to the flat, I'd experiment with using a high pass filter and slowly increasing the turnover frequency until the problem goes away.

 

We have similar issues with the Boomtown Fair held a few miles from our house every year - it is virtually inaudible outside yet the ground borne vibrations mean the bass is very audible inside our house.

 

James.