Author Topic: Accuracy for home night noise measurement  (Read 4386 times)

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Zimbo

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Accuracy for home night noise measurement
« on: July 25, 2012, 02:02:51 AM »
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

FaberAST

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Re: Accuracy for home night noise measurement
« Reply #1 on: July 30, 2012, 10:22:21 AM »
Zimbo,

Quote
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