Measuring Sound

In our business “really loud” isn’t accurate enough for us to help you. We use standard measurements of airborne or footstep noise to provide you with an explanation of your current noise levels, and where we estimate they will be after using our products. Even discussing percentages is not acceptable; your perception of 50% quieter and ours may not be the same. It’s important that you use accurate information to make your decisions for soundproofing products.

What is a dB?

A decibel, or dB, is a unit measure to explain “how loud” a sound is. A sound pressure level of 0 dB represents the bottom threshold of hearing in the most sensitive frequency range of a young, healthy ear, while painful sensations in the ear occur at 120 dB. dB measurements at certain frequencies, Hz, are used to determine STC

Typical Sound Levels

Sound Noise Level * Effect
Whisper 15 dB Very quiet
Speech 60 dB Comfortable
Busy Restaurant 70 dB Uncomfortable
Lawnmower 85 dB Loud
Car Horn 110 dB Very Loud
Jet Taking Off 120 dB Dangerous
Gunshot 140 dB Hearing Loss

What is Hz?

Hertz is the standard unit of measurement used for measuring frequency. Since frequency is measured in cycles per second, one hertz equals one cycle per second. Hertz is used commonly used to measure wave frequencies, such as sound waves. Low frequency is noise you can actually feel- a sub-woofer, mid frequency is where the normal speech ranges occur, and high frequency would be the sound of breaking glass. Low frequency noise is harder to block

What is STC?

STC stands for Sound Transmission Classification. Noise is generated at a constant level, and the reduction of the noise on the other side of a product, wall, floor or ceiling is the STC. We use STC to explain how much noise a product will block when it is added to a wall, floor or ceiling. How much noise it blocks by itself is no indication of how it will work when used with other materials. STC testing includes sound levels at 125, 250, 500, 1000, 200 and 4000 Hz. STC is not the best indicator for low frequency noise levels.

STC Ratings For Walls

STC Rating Description
Poor 30 – 39 Voices easily heard on other side
Good 40 – 49 Home or office noise is significantly reduced
Better 50 – 59 Shouting can barely be heard
Best 60 – 69 Home Theater noise is blocked well

What is IIC

IIC stands for Impact Isolation Classification. IIC is the standard used to measure footsteps. Footstep noise is measured using a tapping machine; basically, a device that has a series of little hammers that hit the floor on a regular interval. The noise level is measured in the room with the machine, and in a room below. The difference in the noise levels is the IIC. Different finished floors, and different soundproofing underlay products are used for comparison. We test the finished floor with no underlay, and then with one of our underlayments; the difference is the IIC for that specific underlayment. IIC values are commonly exaggerated by testing on concrete slabs with a suspended, isolated, very heavy drywall ceiling below- you will not get the same results of your building is wood rather than concrete.

We are here to answer your questions about measuring sound, give us a call.

Complete the form on right or call us at 704-504-1127 to discuss your project and we will provide free consultation, and products that work, every time.


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