How Loud is Too Loud?
Considering noise exposure while mixing
This question is often something that I hear a lot when mixing or consulting at churches. This debate is something that can be an easy answer for some venues, and a more difficult one for others. I would love to share some of my findings and limits that I have previously set in place at the churches where I’ve been employed in a leadership role. Even if you don’t agree with the levels I’ve come to, I hope this research will help you make informed decisions for your own circumstances.
SPL stands for sound pressure level and is expressed in dB or decibels. This is the worldwide accepted measurement for volume. There are SPL meters that can measure the volume of the environment you are in. When looking at an SPL meter, there are many different settings that you can select. Not all of them mean the same thing!
dB-A or dB-C?
Two of the most common settings on an SPL meter are dB-A and dB-C. These two settings are looking at the same thing, yet, measuring it differently.
dB-A is shown in blue and dB-C is shown in red
A-weighted SPL (dB-A) is measured in a way that is more like our human hearing and it subdues the measurement of the sub-frequencies. C-weighted SPL (dB-C) is going to be sensitive to all of the frequencies over the entire range from 20Hz-20kHz.
The National Institute for Occupational Safety and Health (NIOSH), Occupational Safety and Health Administration (OSHA), Environmental Protection Agency (EPA), and the World Health Organization (WHO) all use Leq A-weighted measurements for specifying safe listening levels.
Leq is an average of the SPL over a duration of time and is equated to the exposure the service or event had on the audience. 93 dB LAeq, 60min would represent an average of 93 dB-A over a duration of 60 minutes.
It is important to note that this average will still contain moments when the SPL goes above 93dB.
What are the Observed Limits?
OSHA sets legal limits on noise exposure in the workplace. These limits are based on a worker's time-weighted average over an 8-hour day. With noise, OSHA's permissible exposure limit is 90 dB-A for all workers for an 8-hour day. The OSHA standard uses a 5 dB-A exchange rate. This means that when the noise level is increased by 5 dB-A, the amount of time a person can be exposed to a certain noise level to receive the same dose is cut in half.
The National Institute for Occupational Safety and Health (NIOSH) has recommended that all worker exposures to noise should be controlled below a level equivalent to 85 dB-A for eight hours to minimize occupational noise-induced hearing loss. NIOSH also recommends a 3 dB-A exchange rate so that every increase by 3 dB-A doubles the amount of noise and halves the recommended amount of exposure time.
We can see the NIOSH and the OSHA limits side by side here:
The World Health Organization has set a sound level limit for concerts to be 100 dB LAeq, 15min, and a 140 dB LCeq, Peak for instantaneous limit. (notice the C-weighting here). The 100 dB LAeq, 15min happens to be the same as the NIOSH observed limit as we can see from the chart above.
For an instantaneous impulse noise, we can base the NIOSH on the 85 dB LAeq, 8hr and the 3-dB exchange rate, the allowable exposure time at 140 dB-A is less than 0.1 sec; thus, 140 dB-A is a reasonable ceiling limit for impulsive noise. However, the WHO uses 140 dB-C for this measurement.
My Observed Max Limits on SPL:
Peak, Instantaneous: 140 dB-C, Peak
15 Minute Average: 100 dB LAeq, 15min
60 Minute Average: 93 dB LAeq, 60min
These are the maximum levels for hearing damage to not occur for the audience and should be observed in any concert space, from large arenas to small churches. We should always have hearing protection readily available for anyone attending our concert, show, or service.
For the churches I have been a part of:
As for the churches I have been a part of, the above levels are considerably loud, even with a high-energy worship service. I have modified my expectations to be a little lower to match the overall goal for a high-energy worship service.
My Target Limits on SPL for Church:
Peak, Instantaneous: 115 dB-C, Slow
Peak, Instantaneous: 98 dB-A, Fast
1 Minute Average: 100 dB LAeq, 1min
15 Minute Average: 91 dB LAeq, 15min
60 Minute Average: 85 dB LAeq, 60min
Still too loud?
Even with all this research, it’s likely that my limits will still feel too loud in your circumstance. It’s important to be aware of the recommendations for safe listening levels and to include leadership in the decision-making process wherever possible so you’re on the same page.
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