How to measure decibels and frequency with the Decibel Meter app

Frequency matters

When you're dealing with a noise issue, the frequency of that noise is just as important as the decibel level. A decibel is the loudness of the sound, and measuring decibels can alert you when a sound is more than just a nuisance, but dangerous to your health.

However, decibel levels on their own don't tell the whole story. The frequency of the sound is also very important. The frequency is a measure of how many sound waves per second are produced by a sound, and determines its pitch. A low-frequency sound might be really annoying, but it might not be that loud. The lower frequencies are typically below 150 Hz, and often sound like a deep bass sound that's not necessarily loud, but the vibrations from that sound can travel through the entire frame of a building and disrupt sleep or cause stress.

Knowing both the decibel level and the frequency of an unwanted sound can help you determine the right soundproofing solution. For example, a low-frequency noise won't be stopped by fabric or acoustic foam or fiberglass batts. It often requires mass and decoupling, combined with absorption.

Luckily, there's a free app in Apple's App Store that can measure both the decibel level and the frequency of a sound at the same time. It's called "Decibel Meter," and the developer's name is Ashraf Thoppukadavil.

Here's a Soundproofist video that demos the app in action.

Comments

Two layers of drywall and Green Glue

Another YouTube video: layering drywall I have to admit: I never get tired of seeing other people's soundproofing videos. Here's a video from Acoustical Surfaces that shows two guys building a wall out of 2x4s and insulating them with cotton batts, and then layering two sheets of drywall over each side. They make sure not to overlap the seams between the two layers, and they use two tubes of Green Glue on each 4x8 sheet of drywall. We don't get to hear the results, but if I were them, I might have either staggered the wall studs (since they were building the wall from scratch), or put soundproofing green tape (aka " joist tape ") on every other stud to keep the first layer of drywall from touching the wood (a "fake" staggered wall).

Combining QuietRock and Green Glue together

Two great products work great together. As I've mentioned before, I'm experimenting around with ways to reduce some of the noise problems in my apartment on a tight budget. I think I've found the best combination to date: adding a layer of QuietRock 510 over an existing layer of gypsum drywall with a layer of Green Glue inbetween. This was sort of the best of both worlds: taking a pre-made, sound-dampened drywall and then adding it over a powerful, viscous layer of glue....onto drywall that was already on the wall studs. No demo needed. In this project, I basically added two sound-dampening layers to the original 1950s drywall (one layer in the QuietRock and the other layer created by the Green Glue) to address " flanking noise ": feet, furniture, and shoes pounding on the bare floor of my downstairs neighbors' apartment. The amount of banging, bashing, and foot-stomping sounds coming from their very "wooden" apartment has been severe, and I...

How to measure decibels with the NIOSH sound level meter app

For a quick lesson on how to use the NIOSH (National Institute of Occupational Safety and Health) app to measure decibels and noise, check out my latest Soundproofist video. This handy app is free, although only available for iOS devices right now. It's a great app to use if you want to measure average and maximum noise levels with either A-weighted or C-weighted decibels. You can save each measurement as a report. Learn more about measuring noise and about soundproofing from Soundproofist . Download the free NIOSH app from the App Store and learn more about it from this CDC documentation .

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