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Here’s a great article from the August 2017 Edition of audioXpress, from our own Jim DeGrandis , on acoustic diffusers and diffusion. The article gives an overview of the ‘state-of-the-industry’ as it relates to diffuser design, measurement, and practical application. Jim is a member of the Acoustical Society of America (ASA) and ASTM International.
Here is what we know, and where it’s headed.
For anyone new to the world of acoustics, there is a multitude of terms, coefficients and numbers that are thrown around. This flood of information can seem intimidating, especially to beginners. In this series, acoustician Cameron Girard of Acoustics First® hopes to help you distinguish between what’s useful and what’s not.
Part 3: Perception of Volume
Our ears are wonderful and intricate tools that many of us take for granted. It is very important to understand the idiosyncrasies of our hearing when considering the effect a certain acoustic treatment will make. For starters, let’s take a look at how our ears interpret volume.
Volume (Sound Intensity)
Sound levels (i.e. how loud something is) are typically expressed in decibels (dB). Human hearing ranges from 0dB (threshold of hearing) to 130dB (threshold of pain). The following chart displays common sound sources and their typical dB level.
Do two candles really burn twice as bright?
If one trombonist plays at 70dB, how much louder would it be if another trombonist started playing at 70dB? One might assume that the two trombonists combined would play at 140 dB, but this is not the case. Since decibels are logarithmic values, they cannot be combined by normal algebraic addition. When two sources at the same level play, 3dB should be added to the value to find the combined sound level. So in adding another trombonist, you would really only increase the level to 73dB, a much smaller jump than expected.
“Doubling” the amount of players will double the acoustic power, but what do we actually hear? The loudness perception table shown below displays how these decibel changes are actually perceived by the listener.
Loudness Perception Table
|Change of Level||Approx. Perceived Difference||Volume Gain Factor||Acoustic Power Gain Factor|
|+10dB||“twice as loud”||2.000||10.000|
|– 3dB||“noticeably quieter”||0.812||0.500|
|– 6dB||“significantly less loud/noisy”||0.660||0.250|
|– 10dB||“half as loud”||0.500||0.100|
*Chart Courtesy of David Eagan’s Architectural Acoustics (New York: McGraw-Hill, 1988),
As you can see, doubling the acoustic power (a change of 3dB) would be “noticeable” but not “significant”. It would take a jump of 10dB to make something sound twice as loud. Keep this chart in mind when reviewing acoustic predictions, particularly those that that pertain to noise reduction/control and sound isolation.
Acoustics First® is hankering to announce the first products made with our newly developed AuraGELL-O™ Compound. First realized by Peter Cooper and patented in 1845, this Biosynthesized Bifractive Polyamide has a “sweetness” when combined with our Diffusive Biomass Technology. AuraGell-O™ is a Bio-Polyamide compound which exhibits Bifractive properties, doubling the potency of the Biomass Diffuser Technology by carving the wave in two, thereby creating a phase cancelling stream which functions as a frequency tuned absorber.
The AuraGELL-O™ Infra-Red dissolves low-frequencies, while AuraGELL-O™ In-LIME absorbs the mid-band frequencies (Acoustics First® is cooking up AuraGELL-O™ Ultra-Violet for high frequencies).
Available in AuraGELL-O™ Barrel and Pyramid formats, you get the benefits of classic diffuser styling with the added bonus of the AuraGELL-O™ Biosynthesized Bifractive Polyamide with Biomass Diffuser Technology.
“We loved our AuraGELL-O™ Barrels so much – we went back for seconds!” – Angelo LeMonjello
Call Acoustics First® and get your AuraGELL-O™ Barrels and Pyramids today – because by tomorrow, they will all be devoured!
Update: Due to an outbreak of AuraGELL-O™ weevils, and massive consumer demand, we regret to inform you that this was an April Fool’s joke.
For our first post of 2017, we thought we’d share this video produced by our friends at Graveyard Carz! When the reality show had noise issues with their compressors while filming, they solved the problem by using Stratiquilt™ Acoustic Blankets from Acoustics First®. This video shows a before and after comparison and is a great example of the practical application of these industrial sound control blankets.
As many of you know, Acoustics First® invests a great deal of energy in the development of the science of acoustics. Here are three ways that we are making advances that help people learn and actually Visualize acoustics!
Those interested in sound diffusers have certainly noticed that Acoustics First® has produced a Diffuser Data book, containing all kinds of test data about how our diffusers contribute to the sound in your space. This information is a great advancement and we have worked closely with the ASTM committee developing this test method. Some people wonder exactly how the test produces the data that we report, and we have developed a simulation to show exactly how the sound energy is sampled during this test.
Acoustics First – Diffuser Data Test Demo from Acoustics First®.
We have also made leaps and bounds in using simulations to show the different ways that diffusion develops in a space. Depending on the type and placement of the diffusers you install, the diffuse field will develop at different speeds, at different frequencies. We can now show a couple of simulations of the development of a diffuse field to help you visualize how sound moves in room without treatment and with two different sets of diffuser treatments.
Acoustics First – Room Simulations from Acoustics First®.
Bonus video! Imagine being able to see the Untreated room and the Model D room from a different angle – To be able to move around the outside of the room and see how the sound field develops from a different perspective. Imagine no more! Here it is!
Acoustics First – Sound Field Development Simulation – 3D Panning from Acoustics First®.
If you prefer to use YouTube – you will find the videos uploaded at our YouTube channel here.
We hope these helped you to “look” at acoustics in a whole new way, and stay tuned – more advancements are coming soon!