Open Source Voice Decibel Detector

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  • Project: Microduino open source voice decibel detector
  • Objective: Monitor noise, and it will give an alarm when the threshold is surpassed.
  • Difficulty: Medium
  • Time-consuming: 1 hour
  • Maker: ray
  • Introduction:
    • In this tutorial we will use Microduino product module to quickly set up a noise detector.
    • It can detect the constant noise and give an alarm with buzzer and LED lights.
    • The noise decibel value will be displayed on the OLED screen.

Bill of Material

  • Microduino Equipment
Module Number Function
Microduino-Core 1 Core board
Microduino-USBTTL 1 Program download
Microduino-OLED 1 Show the current db value
Microduino-Duo-v 1 Reduce the overall height
Microduino-Sensorhub 1 Sensor linking
Microduino-Sound 1 Collect voice
Microduino-Crash 1 Switch
Microduino-Buzzer 1 Buzzer, alarm
Microduino-Color LED 1 Alarm and flash
  • Other Equipment
Module Number Function
Micro-USB cable 1 Program download, and power supply
Wooden casing suite 1 The appearance, and fixation
M2 screw 15 Structure fixation
M2 nut 15 Structure fixation
Screwdriver 1 Tool
double-sided taps 2 Structure fixation

Principle of the Experiment

  • Collect voice in the environment through mCookie-Sensor MIC microphone sensor.
  • When the voice is constantly over db threshold, the LED will light and the buzzer will alarm.
  • You should press the collision to remove the alarm.
  • OLED screen real time displays the current environment sound db value.

Program Download


  • Overlay Microduino-Core and Microduino-USBTTL together.
    • Connect Microduino-USBTTL with USB cable, and prepare to upload the program.
    • Note:Please upload programs before stacking all modules together.
  • Open Arduino IDE for Microduino environment(Reference to set up:AVR Core:Getting started
  • Click [tool] bar, confirm board(Microduino-Core) processor(Atmega644pa@16M,5V) selected correctly, and select the corresponding port number(COMX).
  • Click [File]->[open], browse to the project program address, and click "DBDetector.ino" to open it.
  • After all these items are correct, click "→" button to download onto the development board.

Noise Detector Assemble

  • Step1
    • Set them respectively in turn from left to right, namely structure B1,B2,B3,B4.

  • Step2
    • Fix OLED on structure B2 with screw and nut, as shown in the picture.

    • Fix collision switch on structure B1 in accordance with the direction as shown in the picture.
    • Note that it must be same with the direction on the picture, which is related to the overall placement of the collision switch.




  • Step3
    • Put structure B1 adjoining to structure B2.
    • Make collision switch part in structure B1come out from the hollow-out part in structure B2, as shown in then picture marked.

    • Put structure B3 adjoining to structure B2.
    • Put structure B4 adjoining to structure B3.



  • Step5
    • Cover structure A1 and structure A2 up and down and fix with cart slot of structure B5 . Now the noise monitor assembling complete.

    • Finally, insert USB cable into the power supply backplane of Microduino-Duo-v , then the noise tester can operate.

Operating Instruction

  • When noise reaches a certain degree, it will give an alarm.
  • The buzzer will ring, and the LED lamp will light.
  • OLED will show the highest decibels.
  • You can press the collision switch to turn off.


  • Q: Can the triggered sound size and duration be changed?
    • A: Yes, you can change the variable value of voice and maxNoise in userDef.h.
  • Q: Can I close it when the alarm ring?
    • A: Yes, pressing the switch can close it.
  • Q: Why dose mine continually alarm, and turning off the switch has no reaction?
    • A: Notice that if the pin of microphone MIC has been inserted into A0/A1, and not into D0/D1, where is confusing.