Help with DFRobot Sound Meter for noise pollution project
joulz798 2022-07-07 02:12:17 2643 Views5 Replies Hi everyone,
I'm working on a community-based project to measure noise pollution in busy neighborhoods in the city that I live in.
I'm using the DFRobot Analog Sound Level Meter (SKU:SEN0232) connected to an ESP8266 node-mcu module to send results to a central database.
The sensor works pretty well out of box. We're using the code as is. But there is one problem: sensitivity.
For example, if I am in a very quiet room and just exhale from my mouth the sound level jumps to 100+ decibels. In a semi-quiet room the levels are between 60-70 DB.
When benchmarking with very good decibel meter applications on our phone, these values seem to be very high.
My question is, can someone please explain to me if I am missing something here. Should we tweak the code of the sound level meter to make it less sensitive (e.g. lower the sensitivity constant from 50 to 25) or are these reading in fact genuine?
Thank you very much for any help you can provide!
Interesting observation! 100+ dB from a breath seems high. Consider environmental factors – phone placement matters! Also, are you sure the mic isn't faulty? It's possible, especially after intense games like [url=https://motox3mfree.io/]Moto X3M[/url]. Try calibrating with a known sound source before tweaking the code. Perhaps compare results with another phone.
Zula.Reed Hey, I've seen this issue before! That 100+ dB reading for just exhaling is definitely too high—it sounds like the constant 50 in the code is the wrong calibration factor for your exact setup.
That constant is essentially the sensitivity multiplier needed to convert the raw analog voltage reading into a correct decibel (dB) level. It often needs to be tweaked since it depends on your specific mic, amplifier, and ADC reference.
Trying to lower it, like to 25 as you suggested, is exactly the right next step! You'll need to use a known source (like a commercial SPL meter or a properly calibrated phone app) as your reference and adjust that constant until your readings match the reference meter.
You may also find this free tool helpful. https://noisemeter.co/
Olivia.Anns Hi, Please suspend the sensor to eliminate the desktop sound transmission.
Winster Yo, for a school noise pollution project, you don't need to break the bank on a fancy meter.
Honestly, just grab a cheap Type 2 digital sound level meter online. Make sure it does the A-weighting (dBA) thing—that's key for noise pollution since it measures what humans actually hear.
If you're really on a budget, an app like Decibel X on your phone can actually be pretty decent, especially if you calibrate it with a known sound source first. It won't be pro-grade, but it's totally good enough to get some solid data points for a school project. You gotta get out there and log the difference between the street and the park! Good luck!
Feel free to use this tool—it’s free. https://noisemeter.co/
