Measuring Acoustics: the Right Way or the Easy Way

Original text by Acoustic Blinds and Curtains. Acoustic Blinds and Curtains is the brand for Acoustic Blinds and Curtains in Australia, offering acoustic solutions in window furnishings — with an industry-leading range of acoustic fabrics, including exclusive fabrics, and a custom noise reduction solution.

"Smartphones are more commonplace than ever – and so are apps that purport to measure the acoustic properties of a space. However, a series of experiments conducted to compare the performance of smartphones versus ‘traditional’ sound level meters revealed that while smartphone devices can offer some indication of sound levels, they aren’t as accurate or reliable as sound level meters designed and calibrated in accordance with international standards.

These findings prove that customers should think twice before using a smartphone app when measuring and analyzing sound."

From our experience, apps do an adequate job of measuring signal strength (volume) but volume is only a small factor when mastering the perfect soundscape. A sporting arena has different acoustic needs than a school and it’s more than just volume.

"A study conducted by two researchers, Rhys Brown and Lee Evans, compared an Apple iPhone with a traditional sound level meter for its ability to measure sound pressure level and reverberation time from various sound sources. They found enough limitations in the smartphone to recommend that it not be used when conducting acoustics tests."

I continue to wonder why more clients and/or architects/interior designers don’t utilize a professional Acoustician. It’s not uncommon to see projects come through with a half million dollar budget with no plan or appetite for professional acoustic recommendations. More surprising to me is the cost is not prohibitive by any stretch either. A manufacturer can only do so much. And most can’t do anything to accurately assist. To solve this potential gap we have developed a frequency and reverb modeling tool that allows us to select the right materials and the right placement of those materials, from hundreds or thousands of miles away. It’s not perfect but it sure beats a board, a dart, and a blindfold.

"Acoustic Blinds and Curtains partners with acoustics experts who not only use professional equipment but are also skilled at conducting testing in strict conditions. They ensure the following conditions are met when conducting a test:

• A constant sound source is needed. Tests can be more accurately performed when a speaker is set up to play white noise, pink noise or other specific noise at a constant intensity that is well above the ambient, background sound level."

Constant and consistent. Many Acousticians will use actual objects that make a sound versus a speaker that plays the sound or frequency.

"• A test needs to be conducted over a long period of time – from minutes to hours – to account for any variations. Acoustics experts use a measurement called equivalent continuous sound level to smooth out any variations. 

• Testing needs to be conducted using ‘no curtain to curtain’ versus ‘open to closed curtain’ as the curtains work by absorbing sound in the space being measured."

In our case, panels, baffles, and clouds plus other solutions that also help clarify sound and mitigate noise.

"Acoustic experts are also required to take noise measurements in accordance with specific international standards and guidelines. That means using laboratory-calibrated sound level meters such as the NTI Audio XL2 audio and acoustic analyzer. It’s a calibrated Swiss-made sound level meter, acoustic analyzer and vibration meter that far outperforms the smartphone for its ability to measure and analyze sound.

Should a smartphone be used for acoustic measurements? Brown and Evans’ study showed that smartphones can give an indication of noise and reverberation levels – but they are not accurate or reliable compared to professional-grade equipment.

Acoustic apps can be somewhat useful to the general public for making quick measurements – and as long as they understand the limitations of their devices.

But when it comes to taking an accurate measure of the sound in a given space, it’s clear that smartphones can’t do what professional-grade sound measuring equipment can."

A professional will also recommend the right mix of reflective materials vs absorptive materials in a building or space (reflective for keeping sound separated, absorptive for keeping sound clear), electronics such as amplification and white noise machines, additional solutions like wall coverings and HVAC sleeves, and hardware options like vibration canceling speaker mounts. Did you know they now make drywall installation hardware that helps cancel noise in a room? An Acoustician does…

Back to Articles