Hello all. I’m new to Arduino development. I have some programming experience but mostly in high level languages.
I am trying to build a 24/7/365 noisemeter. I live in an area that has a severe noise problem but the citizens cannot fight back against the offender without empirical data. They are claiming their noise does not exceed 55 dB but my iPad and cellphone noisemeter software consistently show 85 dB + noise levels throughout the day. Unfortunately, I don’t have a 24/7 surveillance of noise levels nor is it practical to keep an iPad or cell phone on the roof.
So, I need advice on how to create a noisemeter with the following requirements:
- Sound measurement accuracy comparable to Type 1 noise meter (NIOSH developed an iPhone/iPad application using the native sound hardware and achieved performance near Type 1 accuracy: NIOSH Sound Level Meter App | NIOSH | CDC ) Ideally the measured dB level would be within 1-2% of what this software is reporting.
- Runs 24/7/365. Should run of AC power via AC-DC converter but must not induce unacceptable levels of noise.
- Logs dB data to either:
- o A computer via Ethernet, WiFi, direct USB.
- o A memory card (SD, microSD).
- Saves in simple comma delimited text format or similar that can be easily parsed. Data logged would be nothing more complex than: date, time hhmmss, ADC_value, dB_level
- Samples at 1 Hz.
- Should be able to do up to 130 dB (like cheap $20 noisemeters). Is a 24-bit analog-to-digital converter necessary to capture this level? I’m not a noise expert by any means but I did read in the Audacity manual that low bit depths cannot capture higher dB levels. I would think that even an 8-bit ADC just outputs 2^8 = 256 levels of voltage measurement, and this would somehow be correlated to a dB level? So would it be fair to say that even an 8-bit ADC could measure within 0.5dB of accuracy if we desire to measure up to 128dB? (256/128=2 levels of resolution per dB).
- Would need some degree of resistance to weather and elements. Breezes seem to generate high dB readings on my phone and iPad. I would assume that covering the microphone from breezes/wind will reduce actual dB measurements. Would it be best to enclose it in a coffee can or something like that?
Thanks for all your advice!