Accuracy for home night noise measurement

Zimbo

Hi

I would like to measure noise level in some apartments at night. I estimate that noise level is somewhere between 25 - 35 dB.

I can calibrate my iPhone with a calibrator. I.e. play 94dB sound at 1 kHz to iPhone and adjust it to show correct reading. How accurate reading can I get with SoundMeter after calibration?

According to IEC 651 Class 2 sound meters should have accuracy of +-1.0 dB and class 3 devices +-1.5 dB.

Class 2 sound meters cost close to 100$ and I found no class 3 devices for sale.

Would a calibrated SoundMeter get close to class 3 device accuracy?

Zimbo

benfaber

Zimbo,

How accurate reading can I get with SoundMeter after calibration?

If you calibrate at 1 kHz, then you should easily be able to achieve accuracy within 0.1 dB at 1 kHz. You should be aware of the current high-pass filtering applied the iPhone's built-in microphone. This issue is discussed on our blog.

If you need true class compliance, then you'll need a dedicated sound level meter build for that purpose. MicW makes a microphone that plugs into the headset jack that they claim conforms to standards for Type 2 sound level meters. However, the iPhone's headset input also passes through the high-pass filter.

We're hopeful that Apple will provide developers with a means to bypass the mic input filter, but we won't know for sure unless/until it happens.

Ben