This mask reacts to sound! Five LED sequins are wired up to a GEMMA and microphone. In addition to the supplies listed on the first page, you will need:

You should also check out the following prerequisite guides:

and optionally take a look at these similar projects for inspiration:

By measuring audio levels in the room, we can use that measurement to control the brightness of the LEDs, giving a pulse-with-the-music effect! Use sewing pins to mock up your sequin design on the mask:

Check out the circuit diagram to get an idea of how the sequins can be arranged-- the positive sides (+) should all face the same way:

Wire connections are as follows:

  • GEMMA GND to sequins (-)
  • GEMMA D0 to sequins (+)
  • Microphone GND to GEMMA GND
  • Microphone Vdd to GEMMA 3V
  • Microphone output to GEMMA A1
  • 150mAh (or larger if desired) battery plugs in to GEMMA's JST port

You can run the wires over the front of the mask, like on the previous page, or you can run the wires on the back of the mask by punching or drilling holes for the wires to pass through. Remove the pinned sequins and drill two holes that match up with the hole spacing on the sequins.

Prep your microphone by tinning and soldering wires to the Vdd, GND, and outout pins.

pass wires through the holes of the mask, then strip and tin them before soldering to the sequins:

Once both positive and negative sides are soldered, pull the wires from the back so the sequin sits flush, then clip the leads with flush snips.

Find a place to put the microphone, which will be different on every mask. We found ajn opening in the fabric lace near the forehead that worked perfectly, but you could put it on the inside facing the wearer's mouth, or anywhere you like.

Solder the sequins and microphone up to GEMMA according to the circuit diagram.

Install a battery using velcro tape. Plug in GEMMA to your computer with a USB cable and make sure GEMMA's power switch is set to the ON position.

Arduino Code

(CircuitPython code appears further down this page)

Load up this sample code using the Arduino software to get you started:

// Sound level sketch for Adafruit microphone amplifier.
// For the GEMMA sequin masquerade mask.

#define SAMPLE_WINDOW 33 // Sample window width in mS (33 mS = ~30 Hz)
#define LED_PIN        0 // DIGITAL pin # where LEDs are connected
#define MIC_PIN       A1 // ANALOG pin # where microphone "OUT" is connected

void setup() {
  pinMode(LED_PIN, OUTPUT);

void loop() {
  // Listen to mic for short interval, recording min & max signal
  unsigned int signalMin = 1023, signalMax = 0;
  unsigned long startTime = millis();
  while((millis() - startTime) < SAMPLE_WINDOW) {
    int sample = analogRead(MIC_PIN);
    if(sample < signalMin) signalMin = sample;
    if(sample > signalMax) signalMax = sample;
  int peakToPeak = signalMax - signalMin; // Max - min = peak-peak amplitude
  int n = (peakToPeak - 10) / 4;          // Remove low-level noise, lower gain
  if(n > 255)    n = 255;                 // Limit to valid PWM range
  else if(n < 0) n = 0;
  analogWrite(LED_PIN, n);                // And send to LEDs as PWM level

CircuitPython Code

Below is CircuitPython code that works similarly to the Arduino sketch shown above. To use this, plug the GEMMA M0 into USB…it should show up on your computer as a small flash drive…then edit the file “” with your text editor of choice. Select and copy the code below and paste it into that file, entirely replacing its contents (don’t mix it in with lingering bits of old code). When you save the file, the code should start running almost immediately (if not, see notes at the bottom of this page).

If GEMMA M0 doesn’t show up as a drive, follow the Introducing GEMMA M0 guide link above to prepare the board for CircuitPython.

This code requires version 2.1 or later of CircuitPython. Earlier versions didn’t yet support PWM output. The “Introducing Gemma M0” guide explains how to load or update CircuitPython if needed.
import time

import analogio
import board
import pulseio

sampleWindow = 0.033  # Sample window width (0.033 sec = 33 mS = ~30 Hz)
ledPin = board.D0  # Pin where LEDs are connected (PWM not avail on D1)
micPin = board.A1  # Microphone 'OUT' is connected here

mic = analogio.AnalogIn(micPin)
pwm = pulseio.PWMOut(ledPin, frequency=1000, duty_cycle=0)

while True:
    # Listen to mic for short interval, recording min & max signal
    signalMin = 65535
    signalMax = 0
    startTime = time.monotonic()
    while (time.monotonic() - startTime) < sampleWindow:
        signal = mic.value
        if signal < signalMin:
            signalMin = signal
        if signal > signalMax:
            signalMax = signal

    peakToPeak = signalMax - signalMin  # Audio amplitude
    n = (peakToPeak - 250) * 4  # Remove low-level noise, boost
    if n > 65535:
        n = 65535  # Limit to valid PWM range
    elif n < 0:
        n = 0
    pwm.duty_cycle = n  # And send to LED as PWM level

Now talk or play music for your mask, and see the LEDs change brightness with the volume!

This guide was first published on Sep 23, 2015. It was last updated on Sep 23, 2015.

This page (Audio-Reactive Mask) was last updated on Jan 25, 2021.