Gig Volumes – Getting it right.

We’ve all been there.  3 am.  Got home from the gig an hour ago.  Can’t sleep because there’s a constant ringing in our ears.

That’s hearing damage, right there – and lets start this article off, by pointing out, that if you do this week in week out, you will eventually go deaf if your ears are ringing after every gig.

So what is “too loud” and what does it mean?

Well….the health and safety people will have you believe that there are levels of exposure which are “safe”.  Like every health and safety rule though, these have a tendency to err on the side of caution – not just a little bit either – in this particular case, you can expect the numbers to work on the lowest possible denominator.

These are the current NIOSH permissible exposure times.

Sound Pressure Level   Sound pressure   Permissible Exposure Time 
115 dB 11.2 Pa 0.46875 minutes (~30 sec)
112 dB 7.96 Pa 0.9375 minutes (~1 min)
109 dB 5.64 Pa 1.875 minutes (< 2 min)
106 dB 3.99 Pa 3.75 minutes (< 4 min)
103 dB 2.83 Pa 7.5 minutes
100 dB 2.00 Pa 15 minutes
  97 dB 1.42 Pa 30 minutes
  94 dB − − − − − − − − − − 1.00 Pa − − − − − − 1 hour − − − − − − − − − − − − − −
  91 dB 0.71 Pa 2 hours
  88 dB 0.50 Pa 4 hours
  85 dB 0.36 Pa 8 hours
  82 dB 0.25 Pa 16 hours

And these are the things to which you can compare SPL levels to.

Sound sources (noise) Examples with distance    Sound pressure    Level Lp dB SPL
 Jet aircraft, 50 m away 140
 Threshold of pain 130
 Threshold of discomfort 120
 Chainsaw, 1 m distance 110
 Disco, 1 m from speaker 100
 Diesel truck, 10 m away 90
 Kerbside of busy road, 5 m 80
 Vacuum cleaner, distance 1 m 70
 Conversational speech, 1 m 60
 Average home 50
 Quiet library 40
 Quiet bedroom at night 30
 Background in TV studio 20
 Rustling leaves in the distance 10
 Hearing threshold  0

So what is the “correct” level, for your gig?

Well that depends on a number of factors.  In an ideal world, your audience wants to be hearing you at between 92dB SPL to 98dB SPL in my opinion.  Below 92dB SPL you start to lose the energy of the performance, and gigs can seem flat and lifeless.  Above that, and (assuming you’re not in the perfect room) the people at the front are going to be suing you for hearing damage after your 2 hour set (if they even bother to stay), and starting to feel quite uncomfortable.

So how do you achieve that? Well, the first thing to point out, is that it’s impossible to get every area of your audience, hearing exactly the same thing, unless you have many multiples of speakers, and an array of tools for rigging and hanging your speakers.  And, in much the same way, it’s impossible to get the sound pressure level (SPL) exactly the same, across the room without these things too.  But, what you can do, is make a conscious effort to make the sound as consistent as possible.

So – when you’re working with two tops and a sub for example – you need some understanding of how sound dissipates with related to distance.

Basic rules:

  • You will lose 6dB SPL for every doubling of distance. Example:  If dB SPL = 100dB at 1m, it will be 94dB SPL at 2 metres, 88dB SPL at 4 metres, and so on and so forth.
  • Lower frequencies lose their energy before higher frequencies.
  • The SPL scale is not linear – a 10dB SPL increase, is perceived by the average human, as a doubling of “loudness”.

In an ideal world, we’d all be playing in rooms with 10 metre high ceilings we could hang our speakers off of,  and using top end kit capable of producing outputs of above 130 dB SPL.  But we can’t.  So here’s a few things we can all do, to keep the sound to the audience, as constant as possible:

  • Raise your speakers as high as is safely possible.  This not only allows the sound to go directly to the ears of the listener, but keeps even the closest listener, as far away from the sound source as possible.  Given that the drop off of your speakers becomes wider, the further away you get, the height allows you to open the consistent space up!
  • Use a single source for your low frequencies.  Unless you have a massive room to cover and can use delays to bring your subs into perfect alignment, try taking your two subs, and putting them in a single location.  I guarantee it will sound better than a sub on either side of the stage.
  • Read up on comb filtering – what it is, and how to deal with it – it will help you in deciding on speaker placement, as well as system selection!  This article, is a good starting point :CLICK:
  • Mix from the position that the majority of your audience will be standing. I see too many bands, mixing from the side of the stage.  Get your desk or sound man to be listening from the position of the audience – after all, they’re the important ones!!
  • Don’t be too keen to be “rock and roll”.  Sure, it’s great to be like Spinal Tap – but if your SPL meter is reading 110dB SPL, you’re taking away more from your performance, than you’re adding in.

The biggest thing though – is to trust your body – if you’re mixing and finding the sound pressure level uncomfortable, then turn it down – your audience would rather hear you, than be worrying about their hearing.

I would also suggest that every musician on the stage, wears hearing protection at all times, as whilst these levels are perfect for the audience – you’re going to be stood behind, or in very close proximity of the FOH in many situations – this has the potential to expose you to very very high SPL’s.  There are many options to protecting your hearing available, but I would recommend custom earplugs or isolating In Ear Monitors – you only get one pair of ears – so they’re worth the expense!

 

All figures quoted above are based on the “A weighting” system of sound measurement, and all information is based on my experience – none of the information contained within these pages should be taken as scientific, and I take no responsibility for its use.

Related reading:  http://justanothersoundguy.wordpress.com/2013/11/23/mixing-within-decibel-limits/

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4 thoughts on “Gig Volumes – Getting it right.

  1. Pingback: What is “Too Loud” | Live Sound Blog

  2. Sometimes being inside a club can be extremely unpleasant if they don’t get the noise level right. Personally I can’t understand why anyone wants to be blasted with sound so loud that your ears are ringing when you leave.

    • There’s a definite balance between getting the energy of live music across, and not hurting people’s ears.

      With a high quality FOH system, for me, that’s approximately 96-98dBa at the listening position.

      • And let us not forget that an employer has a legal obligation to employees to protect them from over exposure to “dangerous” sound levels. By default, “we” the bands and sound engineers working in pubs & clubs etc. surely have an equal obligation in this regard. If a venue were to be sued by a punter for hearing damage caused by a live music event, the blame would no doubt filter down the chain. “We” understand the science, “we” understand the consequences and “we” should be seen to be active in protecting the audience from permanent hearing damage…..in my humble opinion.

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