Arduino based Decibel meter with Sound Sensor

In this project, we will make Arduino based Decibel meter with Sound Sensor & monitor sound level on LCD Display.

Overview: Arduino Decibel Meter using Sound Sensor

You might have seen the decibel meter available in the market that generally measures the sound intensity and level. The sound loudness is measured in terms of decibel. Different sound-producing medium ranging from airplanes to human whisper has a certain level of sound loudness expressed in decibel. Sound waves are the longitudinal waves that have To and Fro motion giving high or low pitch as shown in the image.

The loudness of a sound depends upon the frequency or wavelength or the time required for propagation. Below is the table that shows the level of sound in dB from the threshold of hearing to whisper sound to the bus station or jet planes.

But unfortunately, all the sound level meters available in the market are expensive. that is why I decided to make an Arduino-based decibel meter. Using this sound level meter I can monitor the sound level and intensity on LCD Screen. So I used Arduino Nano along with the sound sensor module with a 16×2 I2C LCD Display.  

The sound sensor generally, reads the analog value of sound which is then converted into the decibel using some mathematical formula.

So in this tutorial, we will use the sound module. This sound module has a mic and an amplifier circuit which is read by a microcontroller.

Before starting, you can check the previous post to get started with LCD Display:
1. IoT based Decibel Meter with ESP8266 & Sound Sensor
2. IoT Smart Agriculture Monitoring & Automatic Irrigation System using ESP8266

Components Required

Now in this tutorial, we’re using Arduino NANO, 16×2 I2C LCD, 3 different color LEDs, and some jumper cables. Here, we are using a breadboard for the assembly. So these are the hardware components required for making this project. All the components can be easily purchased from Amazon. The components purchase link is given below.

S.N	Components Name	Quantity
1	Arduino Nano	1	https://amzn.to/3Hf7zvN
2	LM393 Sound Sensor Module	1	https://amzn.to/3etAakz
3	16X2 I2C LCD Display	1	https://amzn.to/3ezvzxa
4	Multi Color LED	3	https://amzn.to/3ezvOIA
5	Few jumpers wires	10	https://amzn.to/3klh0A4
6	Breadboard	1	https://amzn.to/3H2tbeQ

Microphone Sound Sensor

This is a sound sensor module that I order recently to make a decibel meter. It has a perfect condenser mic that detects the level of sound from the sound-producing medium. The sound sensor is a small board that combines a microphone (50Hz-10kHz) and some circuit connections to convert sound waves into electrical pulses. This electrical pulse is fed to the LM393 which is a comparator IC. LM393 IC helps to digitize the signal and is available at the OUT pin.

This Sound sensor has a potentiometer that is used to adjust the Sensitivity of the OUT signal. It has 3 pins that are OUT, VCC and GND.

Decibel meter with Arduino & 16×2 I2C LCD Display

So here is the circuit diagram we have assembled on the breadboard.

Connect the I2C Pins (SDA, SCL) of LCD Display to A5 & A4 pin of Arduino. Supply the LCD Display with 5V through 5V Pin. Similarly, supply the Sound Sensor with a 3.3V supply through 3.3V Pin. You can also add 3 LEDs of a different color to Arduino D3, D4 & D5 Pins. This LED glows based on different sound intensities. The sound sensor interfaced with the analog pin A0. Here Analog pin is connected because the sound sensor is analog.

So here is the assembly on a breadboard. All the components are assembled as per the circuit diagram.

PCB Designing & Ordering

You can simply assemble the circuit on a breadboard. But if you don’t want to assemble the circuit on a breadboard, you can follow this schematic and build your own PCB. You can download the Gerber file of my PCB Design from the link attached below. The PCB looks like the image shown below.

I provided the Gerber File for the Arduino-based Decibel meter with Sound Sensor PCB below.

You can simply download the Gerber File and order your custom PCB from PCBWay

Visit the PCBWay official website by clicking here: https://www.PCBWay.com/. Simply upload your Gerber File to the Website and place an order. The reason behind most of the people trusting PCBWay for PCB & PCBA Services is because of their quality. The PCB quality is superb and has a very high finish, as expected.

Source Code: Decibel meter with Arduino & LCD Display

This is the simple code that I have written in Arduino IDE. So you need to add the I2C LCD library and you need to define the A0 pin of the Arduino that we are using to detect the sound.

#include <Wire.h>
#include <LiquidCrystal_I2C.h> // Library for LCD
LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2);
 
const int sampleWindow = 50;                              // Sample window width in mS (50 mS = 20Hz)
unsigned int sample;
 
#define SENSOR_PIN A0
#define PIN_QUIET 3
#define PIN_MODERATE 4
#define PIN_LOUD 5

Using this formula we are converting the minimum and maximum voltage generated into a decibel value.

unsigned long startMillis= millis();                   // Start of sample window
   float peakToPeak = 0;                                  // peak-to-peak level
 
   unsigned int signalMax = 0;                            //minimum value
   unsigned int signalMin = 1024;                         //maximum value
 
                                                          // collect data for 50 mS
   while (millis() - startMillis < sampleWindow)
   {
      sample = analogRead(SENSOR_PIN);                    //get reading from microphone
      if (sample < 1024)                                  // toss out spurious readings
      {
         if (sample > signalMax)
         {
            signalMax = sample;                           // save just the max levels
         }
         else if (sample < signalMin)
         {
            signalMin = sample;                           // save just the min levels
         }
      }
   }
 
   peakToPeak = signalMax - signalMin;                    // max - min = peak-peak amplitude
   int db = map(peakToPeak,20,900,49.5,90);             //calibrate for deciBels
 

Similarly, using this function we are displaying the sound intensity in dB using LCD and also providing (Normal, Moderate, and Extreme noise) signal through different color led.

if (db <= 60)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: Quite");
    digitalWrite(PIN_QUIET, HIGH);
    digitalWrite(PIN_MODERATE, LOW);
    digitalWrite(PIN_LOUD, LOW);
  }
  else if (db > 60 && db<85)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: Moderate");
    digitalWrite(PIN_QUIET, LOW);
    digitalWrite(PIN_MODERATE, HIGH);
    digitalWrite(PIN_LOUD, LOW);
  }
  else if (db>=85)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: High");
    digitalWrite(PIN_QUIET, LOW);
    digitalWrite(PIN_MODERATE, LOW);
    digitalWrite(PIN_LOUD, HIGH);
 
  }

Check this complete source code below.

#include <Wire.h>
#include <LiquidCrystal_I2C.h> // Library for LCD
LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2);
 
const int sampleWindow = 50;                              // Sample window width in mS (50 mS = 20Hz)
unsigned int sample;
 
#define SENSOR_PIN A0
#define PIN_QUIET 3
#define PIN_MODERATE 4
#define PIN_LOUD 5
 
void setup ()  
{   
  pinMode (SENSOR_PIN, INPUT); // Set the signal pin as input  
  pinMode(PIN_QUIET, OUTPUT);
  pinMode(PIN_MODERATE, OUTPUT);
  pinMode(PIN_LOUD, OUTPUT); 
 
  digitalWrite(PIN_QUIET, LOW);
  digitalWrite(PIN_MODERATE, LOW);
  digitalWrite(PIN_LOUD, LOW);
  
  Serial.begin(115200);
  lcd.begin();
 
  // Turn on the backlight.
  lcd.backlight();
    lcd.clear();
}  
 
   
void loop ()  
{ 
   unsigned long startMillis= millis();                   // Start of sample window
   float peakToPeak = 0;                                  // peak-to-peak level
 
   unsigned int signalMax = 0;                            //minimum value
   unsigned int signalMin = 1024;                         //maximum value
 
                                                          // collect data for 50 mS
   while (millis() - startMillis < sampleWindow)
   {
      sample = analogRead(SENSOR_PIN);                    //get reading from microphone
      if (sample < 1024)                                  // toss out spurious readings
      {
         if (sample > signalMax)
         {
            signalMax = sample;                           // save just the max levels
         }
         else if (sample < signalMin)
         {
            signalMin = sample;                           // save just the min levels
         }
      }
   }
 
   peakToPeak = signalMax - signalMin;                    // max - min = peak-peak amplitude
   int db = map(peakToPeak,20,900,49.5,90);             //calibrate for deciBels
 
  lcd.setCursor(0, 0);
  lcd.print("Loudness: ");
  lcd.print(db);
  lcd.print("dB");
  
  if (db <= 60)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: Quite");
    digitalWrite(PIN_QUIET, HIGH);
    digitalWrite(PIN_MODERATE, LOW);
    digitalWrite(PIN_LOUD, LOW);
  }
  else if (db > 60 && db<85)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: Moderate");
    digitalWrite(PIN_QUIET, LOW);
    digitalWrite(PIN_MODERATE, HIGH);
    digitalWrite(PIN_LOUD, LOW);
  }
  else if (db>=85)
  {
    lcd.setCursor(0, 1);
    lcd.print("Level: High");
    digitalWrite(PIN_QUIET, LOW);
    digitalWrite(PIN_MODERATE, LOW);
    digitalWrite(PIN_LOUD, HIGH);
 
  }
   
   delay(200); 
   lcd.clear();
}

Now select the correct board and correct port from the Tools menu and then upload the code. once you upload the code sensor get ready and you can measure the sound level intensity on the LCD display.

Monitor Sound dB on LCD Display using Arduino

After the code is uploaded to the Arduino Nano board. All the processes can be observed in the 16×2 LCD display. Now you can play music and observe the value on LCD Display.

Video Tutorial & Guide

So, this is how we made Arduino based Decibel meter with Sound Sensor and 16×2 LCD Display. This DIY project is very helpful for monitoring sound levels in dB. If you have any doubts and queries then do let us know in the comment section. The video tutorial of this project is embedded below.