Sound Levels in the Shop

[fredhargis]

My 3hp oneida DC measured 85 dbC: significantly lower than the Jointer/Planer.

That is extremely quiet for a DC, you are fortunate. Mine runs at 94 db. Years ago when I had straight knives on my planer running it with the DC was so loud I had to wear my shooting muffs. But generally I use ear plugs with a NRR of 25 db.

[Cooler]

In 1970 I worked for a company that sold color painted aluminum sheet with steps for the manufacture of aluminum awnings.  The panels would have to be cut with a band saw, and our company made a band saw with a six foot throat. 

OSHA required noise testing certification, which they did using plywood.  The sound levels with plywood were very low.

The sound level cutting a four foot wide sheet of aluminum was much higher, but we never offered that data to OSHA.  I left the company after a couple of years and I don't know if they ever got in trouble for that. 

But some equipment's noise levels are determined by what they are cutting. (Even a dentists' drill.
   I just got a letter from my dentist and he is now allowed to re-open.  What happened to people with toothaches?)

[OneStaple]

I'm curious as to what all of you are using for taking the sound level measurements. A couple of you mentioned what sounds like specialized devices, which I'm assuming are up to the task.

I'm certainly no expert, but I have looked into the accuracy of sound level measurement apps on smart phones a little because I was curious. It sounds like (no pun intended) there's a surprising amount of variability from app to app and even smart phone to smart phone. There are also potential sources of error from the measurement technique, such as whether there's a case on the phone (likely deadening the sound), whether the phone's mic is pointed toward the noise source (usually meaning the screen should also point toward the noise source, which means you're not looking at the app), etc.. One paper that I read suggested that inaccuracies from smart phones could be off by as much as 25dB for low-frequency sources (they specifically gave machinery and impulsive noises found in a manufacturing environment as an example). That could easily be the difference between safe and not safe.

To me, all of this means taking measurements from a smart phone with a grain of salt, especially when health/safety is on the line. I'd trust a real sound-level device more, but those can also be prone to errors with the measurement technique. None of these comments are directed at anyone in particular, but I just wanted to point them out.

Tyler

[Philip1231]

As I mentioned, my son is an Acoustical Engineer. He has an interest in making very large boats undetectable via sound. He reviewed the Decibel X Pro app that we used and judged it much more than adequate to get a very good idea of sound levels in the shop.

I'm curious as to what all of you are using for taking the sound level measurements. A couple of you mentioned what sounds like specialized devices, which I'm assuming are up to the task.

I'm certainly no expert, but I have looked into the accuracy of sound level measurement apps on smart phones a little because I was curious. It sounds like (no pun intended) there's a surprising amount of variability from app to app and even smart phone to smart phone. There are also potential sources of error from the measurement technique, such as whether there's a case on the phone (likely deadening the sound), whether the phone's mic is pointed toward the noise source (usually meaning the screen should also point toward the noise source, which means you're not looking at the app), etc.. One paper that I read suggested that inaccuracies from smart phones could be off by as much as 25dB for low-frequency sources (they specifically gave machinery and impulsive noises found in a manufacturing environment as an example). That could easily be the difference between safe and not safe.

To me, all of this means taking measurements from a smart phone with a grain of salt, especially when health/safety is on the line. I'd trust a real sound-level device more, but those can also be prone to errors with the measurement technique. None of these comments are directed at anyone in particular, but I just wanted to point them out.

Tyler

[fredhargis]

I bought a sound meter from Amazon that ran $19 a few years back. I didn't have a phone at the time and that was plenty cheap.

[Cooler]

I have this old radio shack meter.  My neighbor was complaining that my TV was too loud.  The meter proved otherwise.



These are available used on E-bay and elsewhere.

[AHill]

My planer when running is the loudest thing in my shop. After I converted the cutter to helix (Byrd), the noise was significantly reduced. I haven't measured it, but it's probably half what it used to be. Math-wise, a 6dB increase is double the sound pressure (or half if the dB is reduced 6dB). I think the linked article takes some liberties with the comparisons. When I worked in the fighter aircraft design world, the sound measurements of a fighter varied quite a bit depending on where you were in relation to the engine. We had to document this in technical manuals for safety reasons. Hearing protection isn't always good enough.

Just a side story. The acoustic signature from very first Space Shuttle launch caused waves in the ocean to move a downrange ship whose radar dishes captured telemetry data (rocket engine data, etc.) from the Shuttle. The radar's slew rate could not keep up with the ship's motion and a lot of data was lost for the first few seconds of launch (a most critical time to collect data!). They had to redesign the radar's gimbal motors and gearboxes. Nobody ever thought to analyze the acoustics's effects on the ocean.

BTW, the linked chart must use funny math. They say the sound of a rural field at 30 dB is one sixteenth as loud as 70 dB. It's way less than that. A 40dB reduction is
1/100th the sound pressure. Pretty sad for a company that specializes in acoustics.

[John Mihich]

I was partially deaf for the longest time so the noise in the shop was no big issue.  Found out that I had fluid in my mastoids that caused my deafness.  I had that fixed last year now the noise is deafening (pun intended).  The only 2 machines I use ear muffs on are the planner and router (hand held and table)  Nothing else seems to hurt my ears.   

Side issue - I now can hear my wife better.