What is Sound: The Correlation Between Sound Power and Sound Pressure

Sound, it is all around at every given point of the day. Whether it is from the music we listen to, the person talking to you, your cars engine, or the wind blowing through the leaves there is no escaping it. Hearing is one of the five senses that the majority of humans rely on and should be protected at all costs and with a good understanding of what sound is, one can help mitigate damage done to their hearing. Sound can be broken down into two parts, sound power and sound pressure. But the real question is, how do these corollate to each other to become the sound that we rely on.

Sound Wave

Sound Power (Watts) is defined as the rate at which sound energy (decibels) is emitted, reflected, transmitted or received, per unit of time. Whereas, Sound Pressure is defined as the local pressure deviation from the ambient atmospheric pressure, caused by a sound wave. Based on these two definitions it can be determined that sound power is the cause that generates the sound wave and sound pressure is the effect or what we hear after the sound wave has traveled to the ear.

This can be summed up in a simple analogy using a light bulb. Light bulbs use electricity to generate a source of light, this means that the power required (also stated in Watts) to cause the bulb to light up is comparable to Sound Power. The intensity of the light being generated (stated in Lumens) would be the Sound Pressure. Sound Pressure is what we would typically hear or call sound. This is what is measured because that is the harmful aspect to our hearing and ears. If the Sound Pressure is high enough and the ear is exposed to it long enough, permanent damage can be done resulting in hearing loss to the point of complete hearing lose.

I have known many people who have lost there hearing either completely or a large portion of it from exposure to loud noises. EXAIR designs and manufactures quiet and efficient point of use compressed air products. These products either meet or exceed the OSHA noise Standards in OSHA Standard 29 CFR – 1910.95 (a).

The OSHA Standard for how long someone can be exposed to a certain noise level

If you are not sure what the noise level is in your facility check out EXAIR’s Digital Sound Level Meter. It’s an easy to use instrument for measuring Sound Pressure levels in an area.

EXAIR’s Digital Sound Level Meter

If you have questions about the Digital Sound Level Meter, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Cody Biehle
Application Engineer
EXAIR Corporation
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What is a Decibel Level?

Decibel level also known as dBA, is how the industry measures sound intensity’s effect on the human ear and is an important value when discussing noise exposure for employees and operators within manufacturing. Manufacturing personnel can be at risk for hearing damage when exposed to high decibel levels if the proper precautions are not taken. For reference, 0 dBA is the softest level that a person can hear. Normal speaking voices are around 65 dBA. A rock concert can be about 120 dBA.

Sounds that are 85 dBA or above can permanently damage your ears. The more sound pressure a sound has, the less time it takes to cause damage. This damage occurs within a sensitive part of our ear called the cochlea, which contain thousands of hair cells used to allow our brains to detect sounds. For example, a sound at 85 dBA may take as long at 8 hours to cause permanent damage, while a sound at 100 dBA can start damaging hair cells after only 30 minutes of listening.

OSHA Max Noise Exposure Chart

The Center for Disease Control (CDC) estimates that 22 million workers are exposed to potentially damaging noise at work each year. Whether you work near machinery, at a sports venue, on a tarmac, or operate a jackhammer—hearing loss is preventable.

Noise may be a problem in your workplace if you:

  • Hear ringing or humming in your ears when you leave work.
  • Have to shout to be heard by a coworker an arm’s length away.
  • Experience temporary hearing loss when leaving work.

If you need to raise your voice to speak to someone 3 feet away, noise levels might be over 85 decibels. Sound-measuring instruments are available to measure the noise levels in a workspace.

The first step to lowering your sound level is to take a baseline reading of your various processes and devices that are causing the noise. EXAIR’s Sound Level Meter, Model 9104, is an easy to use instrument that provides a digital readout of the sound level. They come with an NIST traceable calibration certificate and will allow you to determine what processes and areas are causing the most trouble.

From there, EXAIR has a wide range of Intelligent Compressed Air Products® that are designed to reduce compressed air consumption as well as sound levels. For noisy blowoffs where you’re currently using an open-ended pipe or a loud commercial air nozzle, EXAIR’s Super Air Nozzles are the ideal solution. Not only can they pay for themselves over a short period of time time due to compressed air savings, but your operators will thank you when they’re able to hear later on in life!

 EXAIR has the tools you need to reduce sound level in your processes. If you’d like to talk to an Application Engineer about any applications that you feel could benefit from a sound reduction, give us a call.

Jordan Shouse
Application Engineer

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EXAIR Celebrates Manufacturing Day With A Win For A Manufacturer

In 2012, the National Association of Manufacturers organized an effort to proclaim the first Friday in October (hey, that’s today!) as Manufacturing Day.  According to the Advanced Manufacturing National Program Office (a division of NIST, the National Institute of Standards & Testing,) the purpose of MFG Day is “to raise awareness among students, parents, educators and the general public about modern manufacturing and the rewarding careers available.”

Today is kind of a big deal around here.  Not only is EXAIR Corporation a manufacturer, but many of the companies that use our products are as well.  A lot of us have a rich story, woven into the cloth of the history of American manufacturing (which, in turn, is woven into the larger cloth of American history.)  Have you heard the one about the motivated inventor with an idea to make innovative products who started an operation out of his home that, with inspired direction & vision, became a worldwide leader in their industry?

Yeah; that’s us.  Today, we’re honoring Roy Sweeney’s legacy (he founded the company in October 1983,) and celebrating MFG Day, by publishing a new Case Study, proving out the benefits of the use of EXAIR Intelligent Compressed Air Products in regard to the monetary savings associated with the reduction in compressed air use, and the noise level reduction from the implementation of our engineered products.

You can download the complete Case Study here, but while we’re on the subject, here’s a basic rundown:

  • A roll forming operation used to blow off their product with a combination of loud and inefficient devices: copper tubing and modular flexible hose which is designed primarily for machine tool coolant, but often misapplied for use with compressed air.
  • It worked just fine, but an engineering study noted it as a potential wasteful use of compressed air.  That’s when they called us.
  • By replacing those blow offs with Model 1100 Super Air Nozzles and Model 1122 2″ Flat Super Air Nozzles, their noise levels dropped from 107 dBA to 83.8 dBA.  To put that in perspective, it went from the approximate sound level of a rock concert to that of a leaf blower. (ref: Centers for Disease Control & Prevention: What Causes Hearing Loss?)
  • Compressed air consumption dropped by more than half, from 190 SCFM to 86.8 SCFM…an annual savings of over $3,200.00.  All for an investment of $654.00 (2020 pricing) for those engineered Air Nozzles, Stay Set Hoses, and Magnetic Bases.  That means they’ll have paid for themselves in just under two months.
  • In addition to that, for participation in this Case Study, we’re giving them a generous credit on their order.  Happy Manufacturing Day!

And frankly, I think the engineered products just look better too.

Last but certainly not least, this reduction in compressed air usage decreases the load on their air compressors, reducing the electrical power consumed.  Product impact, along with our own consumption of resources and waste recycling, is a key component of EXAIR Corporation’s Sustainability Plan.  We’re making the world a better place, by making products that make the world a better place, using methods that make the world a better place.  I can’t think of a better way to celebrate Manufacturing Day.  If you want to get in on it, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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MFG Day logo courtesy of nist.gov

Understanding Noise: Sound Power Vs. Sound Pressure

Sound Power and Sound Pressure have been covered a few other times here on the EXAIR Blog. Once here by Brian who made the visual correlation in regards to a speaker and a musical instrument. And here by Russ who breaks down how you calculate sound power level with the below equation!
Sound Power Equation
too lou Sound Power Level Equation
All machines generate sound when they are in operation. The propagated sound waves cause small changes in the ambient air pressure while traveling. A sound source produces sound power and this generates a sound pressure fluctuation in the air. Sound power is the cause of this, whereas sound pressure is the effect. To put it more simply, what we hear is sound pressure, but this sound pressure is caused by the sound power of the emitting sound source. To make a comparison, imagine for example a simple light bulb. The bulb’s power wattage (in W) represents the sound power, whereas the bulb’s light intensity represents the sound pressure.
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Light Bulb
Sound power does not generally depend on the environment. On the contrary, the sound pressure depends on the distance from the source and also on the acoustic environment where the sound wave is produced. In the case of indoor installations for example, sound pressure depends on the size of the room and on the sound absorption capacity of the surfaces. For instance, say the room walls don’t absorb all the sound but reflect parts of it, then the sound pressure will increase due to the so called reverberation effect. (reverberation time is broadly defined as the time it takes for the sound pressure to reduce by 60 dB after the sound emitting source has been shut off). OSHA puts the following limits on personnel exposure to certain noise levels:
Working in areas that exceed these levels will require hearing protection.
EXAIR’s line of Intelligent Compressed Air Products are engineered, designed, and manufactured with efficiency, safety, and noise reduction in mind.  If you’d like to talk about how we can help protect you and your folks’ hearing, call us. Jordan Shouse Application Engineer Send me an email Find us on the Web  Like us on Facebook Twitter: @EXAIR_JS Light Bulb image courtesy of  josh LightWork  Creative Commons License