Noise apps: what you need to know

December 2, 2020

Measuring noise levels with an app on your smartphone or tablet: what could be simpler? But are the measurements accurate? Could these apps be too good to be true? WSPS Specialized Consultant (Occupational Hygiene) Warren Clements shares his perspective on these popular applications.

"How useful the apps are depends in part on what you're using them for," says Warren. "Recording nuisance noise - a too-loud house party next door, or a sound system blasting from the apartment above you - may help back up your complaint to a by-law officer or building manager, but as for assessing noise levels at work, a higher level of accuracy is required."

Here's what you need to know:

According to a study done by the Journal of Occupational and Environmental Hygiene*, in certain situations smartphones, using an effective application and equipped with an external calibrated microphone can collect measurements just as accurately as a Type 2 sound level meter - a device typically used by trained professionals to take noise level readings.
Measurements must be accurate, especially if the noise level may be close to Ontario's maximum time-weighted noise exposure limit of 85 decibels (dB) over an eight-hour work shift. Decibels are based on a logarithmic scale, not a linear scale. For a linear scale, like length, four metres are twice as long as two metres. For a logarithmic scale like decibels, twice as loud as 85 dBA is not 170 dBA. Using a 3dB exchange rate, it's 88 dBA.
We are exposed to noise at work and at home, noise is everywhere. Up to 90% of most production type workplaces, even warehousing, could have noise levels above the maximum allowable limit, estimated one WSPS occupational hygienist recently.

The bottom line

"Using a smartphone app and an external microphone will give you data," says Warren. "But the data might be misleading if you are not using a calibrated, external microphone. How can you make sound decisions if you don't have the right information?"

Warren offers an alternative that doesn't involve any technology. "If you're a metre away and have to raise your voice to a very loud level to make yourself heard, this tells me the noise level may be around 85 db," he says. "But this too is a rough, subjective guideline. Use it only as an indicator that further testing may be required."