Always wondered...

bonut · 05-31-2007, 07:10 AM

Since the level of sound/noise is so important, to me anyway, I was wondering why that, along with that standard IBO/AMO speeds, can't noise level of a particular bow be measured. It wouldn't be that hard to do. I have seen some comparisons between bows and this has been measured. It would just take a set standard when the bow is tested for the speed all with bare bow have a decibel meter at a certain point/distance from the bow. Maybe somewhere somebody already does this, but to me noise level is as important as speed.

Black Frog · 05-31-2007, 07:23 AM

Tough to agree on a "standard" for noise testing.

Where do you sample the noise from the bow? 3 feet in front of? 1 foot off to the side? At 10yds? Is this measured indoor? Outdoors? (that will make a difference)

70# bow? 60# bow? At how many grains per pound? What drawlength?

And then there is A-weighting and C-weighting of measuring sound. Which to use for a bow?

I guess there's too many variables to get everyone to agree to. Heck we can't even get manufacturers to give accurate AMO drawlengthor IBO speed specifications as it is.

fillae · 05-31-2007, 08:54 AM

Also, the arrows they use for speed tests would undoubtably produce the noisiest sound test. It could be done, but would have to be taken with a grain of salt just like the speed tests. It would be a best case scenario, but would not necessarily reflect real world conditions.

bonut · 05-31-2007, 09:19 AM

So the manufacturers aren't going to agree on a standard way to measure noise levels. Has anyone ever got hold of a decibel meter and done there own testing?

KodiakArcher · 05-31-2007, 10:05 AM

Quote:

ORIGINAL: Black Frog

Tough to agree on a "standard" for noise testing.

Where do you sample the noise from the bow? 3 feet in front of? 1 foot off to the side? At 10yds? Is this measured indoor? Outdoors? (that will make a difference)

70# bow? 60# bow? At how many grains per pound? What drawlength?

And then there is A-weighting and C-weighting of measuring sound. Which to use for a bow?

I guess there's too many variables to get everyone to agree to. Heck we can't even get manufacturers to give accurate AMO drawlengthor IBO speed specifications as it is.

Doesn't matter as long as it's done the same for every bow.

Black Frog · 05-31-2007, 10:39 AM

Quote:

ORIGINAL: KodiakArcher
Doesn't matter as long as it's done the same for every bow.

Sure, easier said than done.

And what does the "SAME" mean? It would only be the same for that one location testing several bows. You could do it yourself when comparing bows, but realize the numbers you are getting are fairly meaningless outside of your own personal comparison for that instance.

If the measurements are taken indoors, you'd have to have some standardization of enclosed space volume, and standardization of the sound absorption properties of that volume of space. There is no 'same' in measuring sound levels unless you are doing it in anechoic chamber. They are very expensive to design and build.

And that ain't gonna happen.

Acousticsand sound are very finicky to measure accurately because the surrounding space has a LOT to do with the results. Take aSPL measurement of your bow in a smaller cement-walled basement workshop. It'll be different than if you took that samemeasurement outside in a free-space environment. And it will be different than if you took that measurement in a well-carpeted, high ceiling living room with lots of padded furniture and drapery.

If you think AMO draw and IBO speed specs can be 'fudged' a bit, that is nothing to the way sound readings can be manipulated.

You might say that it would be "close enough" for comparisons, but realize that sound pressure levels are measured in decibels (dB) which is based on a logarithmic scale. General rule of thumb is that 10dB increase in SPL is perceived as twice as loud. So having only a few dB of error can be drastic when actually trying to compare measurements.

Straightarrow · 06-01-2007, 04:22 AM

I agree. Fair testing would be nearly impossible. Cheating would be more than prevelant and the results would would be near meaningless.

Other problems. There is variance among individual bows - sometimes it's huge. Some manfacturers load their bows with sound dampening devices. Other's price the bows lower and let the buyer put his favorite ones on. So, do you test them as they come from the manufacturer, or somehow come up with a standard configuration of dampening add-ons, to compare apples with apples?

Do it really matter what they come from the factory sounding like? Not much in my opinion. I always do extra things to dampen sound on my bows. The quietest bow I've ever heard was a cheap Martin I owned. I took extra pains to make it so. It was probably 3 times as loud off the shelf, before my enhancements. So the fact that a test rates one bow as 1 decibel louder than another, doesn't matter to me. When I get done witht them, neither will be as loud as they were in the test.

Len in Maryland · 06-01-2007, 05:48 AM

Todd:

I worked for a while in a huge anechoic chamber at Westinghouse many years ago. What an experience and what a place. The cost to build that special room with its humidity and other control systems had to be HUGE.

Anyway, variations in sound testing/control can be huge and easily manipulated. Any testing MUST be done using extensive test standards and tools. This industry, because of the its commercial nature, can't do that at this stage of its growth.

Black Frog · 06-01-2007, 08:09 AM

Quote:

ORIGINAL: Len in Maryland
I worked for a while in a huge anechoic chamber at Westinghouse many years ago. What an experience and what a place. The cost to build that special room with its humidity and other control systems had to be HUGE.

Wow- what a fun gig! I always wanted to tinker with a chamber, butnever got to use them for personal use for obvious reasons.

I'm jealous.[:'(]