SPL Metering : Best Practices at Life.Church | Best Practices | Tech Team Knowledge Base

SPL Metering : Best Practices at Life.Church

Updated on September 8, 2020 10:21 AM (EDT)

We receive lots of questions regarding the volume of our Worship sets. Let’s take a moment to discuss SPL (Sound Pressure Level, or volume). How does Life.Church measure SPL and what policies do we have in place to protect our attenders from harmful levels?

Every campus should have a SPL meter. The meter measures in decibels, or dB for short. Some campuses have a software meter which can constantly log SPL.

OSHA REGULATIONS

The Occupational Safety and Health Administration (OSHA) has regulations for SPL exposure. You can find more information on the OSHA website:

LIFE.CHURCH ENVIRONMENT

So let’s talk about SPL in our worship environments. We typically shoot for a 93-94 dBA average over the 18 minutes of worship. With quick peaks and plosives not exceeding 99-100 dBA. This is perfectly within OSHA standards and does not pose a health risk to attenders.

• It is important to be aware of different weighting curves used to measure SPL. We measure in dBA-slow, or “A-weighted, slow response”. The other most common weighting curve you will see is dBC, or “C-weighted”.
  • dBC weighting measures loudness in the full spectrum, 20hz-20khz.
  • dBA weighting excludes the low-end content. So a dBA measurement will read lower than a dBC measurement, but will be more accurate in the damaging high frequencies.
  • Example: A chorus of a loud uptempo song may read around 96-97 dBA, but that same chorus would measure more like 105-106 dBC. So it is very important to understand the differences in weighting curves and use the correct one. The numbers can be misleading if we are not intentional with our settings.

Remember, it is not uncommon for the loudest portion of a song to read around 96-98 dBA. But the number that really matters is the average of the ENTIRE 18-minute worship set. There are loud sections and there are soft sections that balance each other out to achieve the desired overall average of 93-94 dBA.

There are several applications available on mobile devices. These apps are typically not very accurate. If an attender is attempting to monitor SPL via their phone, it is not a valid measurement tool and would not hold up in a court of law.

TIPS AND TRICKS : KEEPING AVERAGE SPL REASONABLE

Over-emphasize dynamics

• As a sound engineer you can help the band achieve more dynamics by riding the faders.
  • Pull down the verses so they are quieter than choruses. Not only will this help your SPL average, it will give the music more impact and perceived presence on the bigger sections when you push the fader back up.

Master buss compression

• Use a small amount of compression on the master buss to tame the loudest peaks and transients.
  • Remember: no more than a 3:1 ratio; 2-3 dB of gain reduction on the LOUDEST sections. (should be little to no gain reduction on verses or softer sections)

Thoughtful arrangements and coaching musicians