Automated Shusher Keeps Conference Loudmouths In Line

Few things are more annoying than being at a conference and having an inconsiderate group conducting a vociferous sidebar that drowns out the speaker. More annoying still is the inevitable shushing; nobody likes being either the shusher or the shushed. So why not take the humans out of the loop and automate the chore of keeping the peace?

Such was the challenge presented to [BotBerg] before a recent conference, who came up with this automated shusher (translation) on short notice. The build is based on the Arduino Nano 33 BLE Sense Deck, a sensor-rich dev board that’s perhaps a little overkill for the job, but hey — you roll with what you’ve got. The board’s MEMS microphone is the sensor used here, which measures the ambient sound pressure level multiple times per second. When the background noise exceeds a potentiometer-set threshold, an MP3 player is triggered to play a sound clip entreating the offenders to pipe down. The whole thing is housed in a playful 3D-printed enclosure shaped like a mouth, which should be sufficient reminder alone to keep yours shut.

This was a quick-and-dirty prototype, of course, and probably could use some refinement. Given the behavior we’ve witnessed at some conferences, we’d say hooking it up to a Nerf turret gun would be a justifiable escalation.

Make Your Own SPL DB Meter With A Microphone And MCU

Measuring equipment such as SPL (Sound Pressure Level) decibel meters may seem daunting, but this article by [Shawon M. Shahryiar] shows that making your own need only have two essential ingredients: a microphone and a microcontroller. Obviously the microphone is for measuring the sound pressure level, and its output is then fed into the ADC of the microcontroller which does some math before sending the result to a display.

[Shawon] runs through all of the theory behind the calculations that have to be performed, before showing the C code that runs on the PIC18F242 8-bit MCU targeted by the prototype setup. The display is a graphical LCD type, capable of displaying the text with values as well as bar graphs indicating the measured levels. For the measurements themselves, the RMS value is taken of 16 ADC samples while the algorithm takes into account the specifications of the Seeed-sourced microphone module, specifically its average 50 dB sensitivity rating.

Although a full schematic is not provided, the essentials are all there for anyone to build their own SPL dB meter using virtually any microphone and MCU with built-in ADC. As the article also notes, opting for a higher quality microphone will yield better result and of course a faster MCU will offer more options, including FFT processing. Since the code itself is fairly basic, it should be easy enough to port it to an ARM-based MCU, which would allow one to use for example a TFT LCD.

Take a peek after the break for a video of the article’s SPL dB meter in action.

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