Volume, speaker quality and tinnitus!

[mattyfish]

Hi folks,

 

Sorry in advance if this has already been covered and I just haven't looked hard enough in the search function.

 

I recently attended two gigs, first being school prom and second a Razorlight gig on their latest tour (which was amazing, had huge LED screens, giant intelligent spot lights plus images projected onto venetian blinds! But I digress!) The sound system at the prom, from outside local production company was very loud- to the point that it was just beginning to distort. Not surprisingly had big ringing in ears later. The sound system at the Razorlight gig, was naturally much better quality speakers and line array design etc. The volume was close to the volume at the prom and I had to be under 15 ft away from the left hand set of subs but afterwards, my ears were not as effected by far. Sorry I don't know any specs about the speaker systems at the events.

 

So what is the reason for this? Is it the quality or frequency response of the speakers, the mix, the size of venue and acoustics, or am I just being imagining it?! I have heard that after spending an evening at a night club in London with top quality designed speaker systems, people can have no, or very little ringing in their ears afterwards...?

 

Second question, for more experienced sound engineers:

 

When mixing loud large events- rock concerts etc, is it unavoidable to send punters home with ringing ears? I for one want to keep my hearing top notch, but when in loud environments surly your hearing will slowly degrade. I know from reading the Red Hot Chili Peppers sound engineers blog that when the crowd gets very loud, he simply cranks up the volume, but do engineers have a responsibility for the crowds hearing? I have read that prolonged exposure to noise levels as low as 70 dB can result in damage to hearing and that if it is not possible to limit exposure, earplugs or ear defenders should be worn. But it seems to me that its some what hypocritical for sound engineers to wear ear plugs, and also essential to listen to the sound to ensure its a good mix.

 

Also, what is the difference between SPL and DB?

 

Sorry for having a bit of a rant! Just be grateful to know what you all think.

 

Regards,

Matt.

[Matt Riley]

Hi Matt,

 

I'll try to answer a few of your smaller questions, however I too would love to hear if there has been any research into the effects of distortion on hearing damage, as opposed to the effects of pure SPL.

 

Which leads me neatly onto:

Also, what is the difference between SPL and DB?

 

When you say SPL I presume you mean dB SPL. This splits down into basically two bits. The dB bit and the SPL bit. The decibel is a logarithmic unit of measurement. Which is great, but doesn't tell us much unless it is relative to something. That's where the SPL bit comes in. This imposes a reference to the decibel. It stands for Sound Pressure Level, and it is used for measuring loudness from acoustic sources. The reference for this is the threshold of human hearing, 0 dB, equivalent to 0.00002 Pa.

 

But what about this 'A' or 'C' weighting thing then? Think of that like an EQ put over the microphone to make it have the same frequency response as the human ear, so the readings we get are actually indicative of how loud it is to a person.

 

But it seems to me that its some what hypocritical for sound engineers to wear ear plugs

 

The average gig for me leaves about 10 hours exposed to concert levels, and if I were touring that would be every day for months. This is compared to the punters, who voluntarily endure a few hours of loud music each week, because they enjoy it. At our venues, we also have loads of earplugs to dispense to staff and people who come to us complaining it is too loud.

 

but do engineers have a responsibility for the crowds hearing

Yes, and in an ideal world, all my mixes would be between 85-90 A weighted for rock stuff. However in many gig situations there is an enormous amount of pressure from the people paying your bills to make it loud - lots of these people can have hearing damage from going to too many concerts. Also, crowds are rather noisy as well, with some big gigs getting well over 95 dBA from screaming girls alone at FOH. So you're fighting that, because if people can't hear the band, then they complain, and promoters and tour managers start to get "emotional".

 

HTH,

 

Matt

[charlyfarly]

Also, crowds are rather noisy as well, with some big gigs getting well over 95 dBA from screaming girls alone at FOH.

 

That is particularly unpleasant. After a while it burns right into your brain. Ditto goes to the jerks who stand right behind or beside the mix area and whistle loudly at all oppurtunities :)

[niclights]

Yes, unfortunately everyone hears things differently and sometimes there are silly pressures from bands/tour managers/record companies etc.

 

Most of the time it is avoidable though - the only real constraints (other than screaming teenagers!) are overcoming levels coming from on stage.

 

On the same systems over many years I've heard every conceivable quality of mix from the truly baffling to sheer perfection. Most pro level equipment is capable of producing both amazing and awful results depending on the engineering. It is very unlikely there is ever any actual distortion on these systems. If an engineer gets the gain structure all wrong channels can be clipping on the desk/in effects machines (soooo often!) or on dynamic inserts, but clipping on amplifiers would be disastrous for the drivers and is usually prohibited by combination of controllers and amplifiers.

 

On a less 'professional' system you might be prone to more of the nasty frequency ranges thanks to more crude/poor quality high frequency drivers and horns, but assuming some form of system equalisation is available then these areas can be brought under control in just the same as a top dollar system can be made to sound awful.

 

I very much believe that the sound engineer should be responsible in the same way a lighting engineer should be responsible for use of strobes etc. They should never be made to feel intimidated by management to do something they consider unsafe. They are, after all, the engineer!

 

As with Matt, our venues have earplugs available to anyone who requires.

 

However, it is my understanding that headphones (or even worse, in-ear types like I-Pod) are far more damaging than a huge great stack of stadium PA due to the huge pressure levels created in the tiny space between transducer and eardrum. Commonly many studio engineers suffer from tinnitus after years of wearing headphones yet in live engineers it is less common. They tend to suffer from grumpy old git syndrome instead. :)

[Jivemaster]

With simple systems the first "too loud" comments usually mean there is too much distortion. Few punters can accurately say why it seems loud.

 

Today's GREAT systems can sound crap if they are badly set or really good when well set, and then they can produce high levels of good sound without distortion.

 

On the subject of noise induced hearing loss. There is a LOT of high level maths, empirical science, and idle chat. Currently no-one knows all the answers. It is however YOUR own and only hearing so some wisdom will help a lot. Turn down the in-ears on walkmans etc.