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 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).
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.
When trying to explain or state a number associated with how loud a sound or noise is it can be somewhat confusing or at the very least, ambiguous. This blog will help to make it clear and easy to understand the difference between Sound Power and Sound Pressure.
Sound Power is defined as the speed at which sound energy is radiated or transmitted for a given period of time. The SI unit of sound power is the watt. It is the power of the sound force on a surface of the medium of propagation of the sound wave.
Sound Pressure is the sound we hear and is defined as the atmospheric pressure disturbance that can vary by the conditions that the sound waves encounter such as furnishings in a room or if outdoors trees, buildings, etc. The unit of measurement for Sound Pressure is the decibel and its abbreviation is the dB.
I know, the difference is still clear as mud! Lets consider a simple analogy using a light bulb. A light bulb uses electricity to make light so the power required (stated in Watts) to light the bulb would be the “Sound Power” and the light generated or more specific the brightness is the “Sound Pressure”. Sound just as with the light emitting from the bulb diminishes as the distance increases from the source. Skipping the math to do this, it works out that the sound decreases by 6 dB as the distance from the sound source is doubled. A decrease of 3dB is half as loud (Sound Pressure) as the original source. As an example sound measured at 90 dB @ 36″ from the source would be 87dB at 54″ from the sound source or 84dB at 72″.
We at EXAIR specialize in making quiet and efficient point of use compressed air products, in fact most of our products either meet or exceed OSHA noise standards seen below.
EXAIR also offers the model 9104 Digital Sound Level Meter. It is an easy to use instrument for measuring and monitoring the sound level pressures in and around equipment and other manufacturing processes.