Enjoy the following thread excerpted from the Live Audio Board (LAB) here on PSW…

Topic Posted By Scott
I’ve been told that a church in L.A., with 8.000 seating, hit something like 172 dB at the console. Is this possible? Someone else told me there’s no way to exceed 130 dB at the board. So I’m looking for the highest dB level anyone’s seen at the house console.

Reply By Tom Danley
172 dB is loud, but is a level that can be produced in air. An array of six of the levitation transducers we formerly made at Intersonics could produce about 175 dB at the center of the array, at 21 kHz. Such a sound field could actually levitate dense objects like lead or tungsten, or could support less dense objects like glass and ceramic at temperatures up to about 2,500 degrees (Celsius).

At 175 dB, one feels the sound as you move your fingers through it, and if you allow a small crack between fingers, you get a good burn from acoustic friction. And if you place an unlit cigarette in the sound field, it ignites from acoustic friction, and sound-absorbing foam disintegrates/melts.

Reply By Bink
Gee whiz, Tom, what’s left for you in the way of entertainment? Doesn’t it seem sometimes like you’ve pretty much been there and done all that? Next time my lights go dim for a few seconds, I’ll know you’re out there somewhere cooking up a new project.

Reply By Frank Aponte
I usually average about 122 dB at FOH when mixing MDO (formerly known as Menudo). This is generally considered very loud.

There are stories about a documented reading of over 132 dB during Menudo’s hey-day in the 1980s. But I believe this was actually the crowd noise of 100,000 screaming girls in a soccer stadium, either in Mexico or Brazil.

The average crowd noise during most shows will hover around 115 dB to 118 dB (mostly centered right around 4 kHz), sustained for the entire show. I’ve been known to hide under the desk when the screaming drowns out the PA.

172 dB? Not very likely.

Reply By Nathan
A friend of mine is a huge car audio buff and master installer, and has outfitted many SUVs for SPL contests. He attended a competition in which one of the officials was inside the car before they tested it, hooking up his calibrated microphone, when someone started the tone burst generator and pumped out 170 dB at 50 Hz. It killed the official.

Reply By Mike
Sniff, sniff . . . I smell an urban legend!

Reply By Bruce
If the threshold of pain for the human ear is near 128 dB, and every 3 dB is perceived as twice as much and takes twice as much wattage, you would be more than 14 times higher in SPL than the threshold of pain. Think about it.

Reply By Ralph
Actually, that number is not 14 – it’s 2 to the 14th power, which is 16,384. So take the amount of power it takes to reach 128 dB at FOH, and multiply that by 16,384.

If it was a very small church and you put in 10,000 watts, you might reach 128 dB at FOH. To reach 172 dB in the same venue, you would need 164 million watts.

NOW think about it.

Reply By Scott
The threshold of pain is frequency dependent; and is also personally subjective to a slight degree. 108 dB at 3 KHz is stupid, 128 dB at 30 Hz is nice.

Reply By Barry
Human hearing sensitivity is at least 40 dB less at 30 Hz than it is at 3.1 kHz. One can experience pain at 100 dB with a 3.1 kHz tone generated alone and 130 dB of 20 Hz is quite enjoyable.

Reply By Jim
Maybe the sound board is inside one of the loudspeaker cabinets?

Reply By Chris
More like, maybe the sound board is tied to the tower where the Space Shuttle gets launched?

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