So I measured volume levels again, this time using pink noise. Here is the raw data from this little science experiment.

I ran the noise at 75 dB because 85 dB of pink noise is REALLY LOUD and annoying. I figured that the exact level at which it is running didn't really matter, as long as it is in the same ballpark as 85.

As you can see the results were less sporadic, but still show the same general pattern of loud and quiet areas.

My question is, does anyone know how to convert this into a color coded map?

I thought I would share something I just shared with our multimedia volunteers.

By serving [with excellence] you are helping to
• Maximize the impact of the Message
• Minimize distractions
• Remove obstacles to worship
• Create transformational moments

We are each doing our part on Sundays to help people believe in Jesus, belong to his church, and become committed to his purpose.

Thanks for working for his mission.

So last week I started work on our project of mapping the decibel levels in the sanctuary. I had to decide on a method. The mixer is equipped with a sine wave tone generator with a sweepable frequency. This makes a constant monophonic sound whose volume can be set with a knob. I set the volume so that the meter read 90 dB at the mixer and turned the frequency to 1kHz, a sort of mid-range frequency. With some earplugs, I went around to strategic areas in the sanctuary and wrote down the volume for that spot. I was surprised to find what I did.

First, that tone generator is REALLY annoying. At that volume level, even with my hands over my ears, it felt like the noise was in my head. Unpleasant. Second, the volume was unpredictable. I originally thought that the very front rows would prove to be the quietest spots in the room. I was wrong. I was also surprised to find out that the sound levels in some areas on the main floor were louder than they were behind the mixer.

Another observation I made was the drastic volume difference between areas only a few feet from each other. Often, the end of one short row was more than a few decibels louder or quieter than the one at the other end. On the longer pews, the difference was drastic. I also noticed that the height at which I held the SPL meter seemed to make a difference so I tried to hold it at ear level for an average person.

Please take a moment to look at the map. What do you notice about the sound levels? Where are the quietest areas in the sanctuary? Where are the loudest? Does anything surprise you?

Here are some caveats. As Chris Sabatke pointed out, using a monophonic tone such as the one produced by the mixer opens us up to some anomalies for that frequency only. The room might be "more sensitive" to some frequencies than to others. Some frequencies build up in some areas due to the unique shape of the room while others cancel out. Chris suggested using white noise, pink noise, or brown noise (not brown nose). You can listen to audio examples and read explanations on Wikipedia. While these types of noise are each different, they are useful because they contain all the frequencies of sound that we can hear, so we might get a more accurate reading of the levels.

Here is a good article on mix building and EQ by John Mills, a live sound expert who runs the mix for guitarist/worship leader Lincoln Brewster, on his blog, TechTraining101.com. If you haven't already, I would suggest creating a log-in and password if necessary to access these articles for free.

He stresses cutting as opposed to boosting frequencies in the EQ because, to put it in layman's terms, it sounds better.