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Author Topic: Acceptable volume statements  (Read 10019 times)

Lee Buckalew

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Re: Acceptable volume statements
« Reply #20 on: June 28, 2009, 08:44:22 AM »

It is rarely about SPL alone but is more frequently related to frequency and SPL combined with distortion.  
A very clean and accurate system is not perceived to be as "loud" as one that is producing lower dB/SPL but is running it's amplifiers into distortion.  I have had to build distortion into one system controller setting because this particular client had a group that used the system (this setting was only for that group) and they were never happy with any system until it was clipping and running into various modes of distortion.  This was true even after we put in a system that could keep the room at a continuous 110 dB/SPL with peaks over 120 dB/SPL.  They were not happy with that as it was "not loud enough", add distortion and 90 - 95 dB/SPL was "loud enough".

That said, often High dB/SPL is used in a misguided attempt to create "energy" when the issue is really frequency response or a lack of it.  Having subs that actually respond below 30Hz at high SPL is critical to hear those 5 string bass guitars well.  Many "Subs" out there just aren't.  
In terms of perception of energy vs. "loudness" (yes, I know it is an incorrect use of the term loudness), properly designed systems with extended frequency response, flat frequency response and a good/proper use of compression on individual inputs will go a very long way toward taming the "It's too loud" syndrome.

Hear is the listing from NIOSH regarding acceptable levels.  Please also note that it does not define a frequency range for the exposure.  It tends to target mid and high frequency while substantially higher low frequency levels can be utilized without a similar rate of damage to hearing.

index.php/fa/409/0/

European standards are actually lower than these.  Many concert venues regulate the maximum level.  If we don't do this ourselves regulation will happen, not to mention that SPL exposure is additive so, if someone listens to their car stereo at 95 dB/SPL on the way to church and then worship averages 95 and then they listen in the car again or have a rehearsal later in the day it all adds up and the ears don't have time to reset.  This is one reason that musicians, Worship Leaders included, who rehearse for half an hour or more prior to service frequently believe that the level has been turned down.  Congregants just arriving think it's fine but the WL wants it turned up because his/her ears have already begun to go into compression.  They actually have chemical transmitters and receptors that create a compression effect, the longer they are "in compression" the longer it takes for them to normalize again.  This is why, frequently, speaking/preaching that occurs in the middle of a service must be turned up substantially from a brief, early, sound check.  After you have had an hour of relatively high energy/level music your ears have adjusted to this level as normal and the lower speaking level is now not high enough.
I expect that it won't be long before a church is sued for hearing loss by a volunteer band member due to monitor levels.

When I bring this up I sometimes get the comment that I'm too old (I'll be 40 this year) but I have done concert work for years and love loud, high energy systems (115 Db/SPL sustained average at mix position was one show spec, that was too loud as it definitely causes hearing damage for a 2-3 hour show but it was in the artists rider).
When you try to achieve high energy merely by being loud with systems that are not capable of producing music exceptionally you create problems and you don't achieve your goals.

By the way, in an average audio class of 12-15 students (I teach at a college) when we do listening tests my hearing in the high frequencies is consistently better than that of all but 2 - 3 of the 18 - 24 year olds in the class.  I take care of my ears because they are the tools that I use to make a living.

This is an issue where quantity can not make up for quality.

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Lee Buckalew
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Brad Weber

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Re: Acceptable volume statements
« Reply #21 on: June 28, 2009, 11:20:59 AM »

I have to say that I have had somewhat the opposite experience, many people seem to associate "loud" with pushing a system and artifacts such as clipping and distortion, thus some well designed and performing systems are not perceived as being as "loud" as they actually are due to the lack of these artifacts.  I think that in some cases people don't actually need a system that can get louder, they need their's 'detuned' so that it sounds "louder" at the same SPL levels.

While a neat looking chart, I wish that they did not post things like that as it is very misleading.  NIOSH is still a long term noise exposure criteria and still based on 8 hour periods.  So you cannot look at the numbers presented in that chart as relating to compliance, only as showing what would be a violation.  Thus the chart is not actually saying that 94dBA for one hour is permissible, any compliance would also depend on the noise level exposure for the rest of the relevant 8 hour period, but rather that an exposure to greater than 94dBA for one hour or to 94dBA for longer than one hour would be a violation.

The idea of temporary threshold shift is a common one for clubs.  The DJ starts the night at one level but as the night goes on their exposure over time results in increasing temporary threshold shift and as a result, their continuing to bump up the levels to offset the shift they experience.
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Brad Weber
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Lee Buckalew

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Re: Acceptable volume statements
« Reply #22 on: June 28, 2009, 11:40:50 AM »

Quote:

I have to say that I have had somewhat the opposite experience, many people seem to associate "loud" with pushing a system and artifacts such as clipping and distortion, thus some well designed and performing systems are not perceived as being as "loud" as they actually are due to the lack of these artifacts. I think that in some cases people don't actually need a system that can get louder, they need their's 'detuned' so that it sounds "louder" at the same SPL levels.



Brad, You are saying what I was.  Many people associate "Loud" with distortion and artifacting.  Beyond that many churches make their services far to loud in an attempt to create a sense of "energy" when what they are actually looking for is impact.  I would venture to say that most (O.K. I'll get some arguments here) church sound systems won't accurately reproduce live music in full range.  Most have neither the frequency range (bandwidth) or the headroom.

I was trying to show with the NIOSH chart that it is a cumulative effect and all prior sound exposure, as long as your ears don't have time to shift the threshold back, has a bearing on how an individual perceives the sound they are hearing.  
It is a fascinating combination of chemical and mechanical components in the ear that seem to be what causes this.  
This threshold shift occurs throughout the day with each of us.  It can be seen in many households where one person gets up earlier than others (quiet environment), they need a tv turned up very low 1st thing in the morning to "hear" or understand the audio on the news.  After coming home from work, in order to achieve the same perceived level, you have to have the tv turned up higher.  This could be some other noises causing some masking but it is also the result of exposure during the day.  

Check out how loud the wind is in your car if you drive on the highway with the windows down.  You'd be amazed at the sounds that you are exposed to throughout a day.  
All of these things change our perception of "loudness".  That's one of the (many) major factors in differences between rehearsals and performances.
What happens when one of your musicians rode his Harley to the rehearsal and then you rehearsed for 3 hours but on Sunday he came with the family in a very quiet sedan.  During sound check his monitors all of a sudden "got louder" even though they didn't really.

Fascinating subject.

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Lee Buckalew
Pro Sound Advice, Inc.
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Brad Weber

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Re: Acceptable volume statements
« Reply #23 on: June 28, 2009, 12:28:52 PM »

It think it greatly comes down to SPL being an absolute value with a defined reference whereas "loudness" is a perceived value with an undefined reference that may vary by individual or situation.  And using potential hearing damage as a guideline for levels seems to be handicapped by there being limited information addressing anything other than either instantaneous effects or the effects of long term workplace exposure, neither of which is typically applicable for church services.
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Brad Weber
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Lee Buckalew

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Re: Acceptable volume statements
« Reply #24 on: June 28, 2009, 12:46:18 PM »

Brad, I would agree.
However I would qualify the statement that SPL is an absolute as it matters what weighting you are using to measure it and even what the measured dB/SPL is as this effects what weighting you should use to approximate an averaged Fletcher-Munson contour.
Further, using a single measurement like dB/SPL does not take into account the frequency's being measured.
I think having some standard that volunteers can follow with a meter is great.
It should be different for speaking and music.  Probably even for tracks vs. Live.

It is also critical that the quality factor be able to be addressed.  I believe that this is where most of these problems lie.  Variations in mix quality (eq., compression, levels of individual instruments, etc.) from one mixing person to another.  Consistency develops into the perception of "it sounds right" to the congregation but, just as practice does not make perfect it only makes permanent (perfect practice or practice with constant improvement makes perfect) we must educate people mixing as to what their leadership wants their church sound to be and then we need to help them to have all of their volunteers be able to emulate this.

Only when there is a consistent mix can relative judgements be made from service to service or week to week.  Outside of this "Too Loud" may actually mean the guitar was really hot from 3kHz to 6kHz and it made the overall mix painful.  This could happen even with a measured SPL that was within whatever approved range was decided upon.

I am trying to point out that it's not a matter of "we ran the music at an average 90 dB/SPL so it was the same as last week", it's much more complex but many try to make it that simple without understanding the complexity.  

I will use a racing analogy.  Asking people who have not been taught how to create a "good" mix (must be defined by the church in question) or been given training in the church's definition of a good mix but telling them to merely maintain a certain SPL is like telling a person that all they need to do to win the Indy 500 is keep their average speed at a certain predefined measurement and it's as simple as that.  Then letting them loose in the Indy Car.  The result will most likely be somewhere between disappointing and disastrous.

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Lee Buckalew
Pro Sound Advice, Inc.
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Re: Acceptable volume statements
« Reply #24 on: June 28, 2009, 12:46:18 PM »


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