See what the sounds around you look like with Raspberry Pi Pico

Post Syndicated from Ashley Whittaker original https://www.raspberrypi.org/blog/see-what-the-sounds-around-you-look-like-with-raspberry-pi-pico/

Raspberry Pi Pico powers this real-time audio spectrogram visualiser using a digital microphone to pick up the sound and an LCD display to show us what those sounds ‘look’ like.

See Sound in Real-Time Using Your Raspberry Pi Pico

First things first

OK firstly, let’s make sure we know what all of those words mean, because ‘audio spectrogram visualiser’ is a bit of a mouthful:

  • A ‘spectrogram’ is a visual way of representing signal strength, or “loudness”, of a signal.
  • The ‘visualiser’ bit comes in when these frequencies are presented as waveforms on the little screen.
  • And the ‘audio‘ is simply because Sandeep is visualising sounds in this project.
Sadly, Sandeep’s machine can’t tell you why the baby is crying

Perfectly portable sound monitor

This pocket-sized device can be carried around with you and lets you see a visual representation of your surrounding audio environment in real-time. So, if you wander into a peaceful bird reserve or something, the LCD display will show you something very different than if you were in, say, Wembley Stadium during an FA Cup final.

Above, you can see Sandeep’s creation in action in the vicinity of a crying baby.

See Sound in Real-Time Using Your Raspberry Pi Pico

Hardware

That is a satisfyingly affordable hardware list.

How does it work?

In the video below, you can see there is a direct correlation between the original audio signal’s amplitude (on the left) and the audio spectrogram’s representation of the signal on the right.

The Microphone Library for Pico captures data from Sandeep’s digital microphone. And Arm’s CMSIS-DSP library processes the audio in real-time, then transforms it into spectrograms. These are then displayed one row at a time on the LCD screen using the ST7789 Library for Pico.

Maker Sandeep Mistry created the original project guide on behalf of the Arm Software Developers team. Check out his other tutorial on how to create a USB Microphone with the Raspberry Pi Pico.

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