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0.5.1 • Public • Published

Clap detection module for node js


ClapDetector is a hand clap detection module for nodejs (iojs). It detects a clap or a series of claps and allows you to trigger callbacks whenever these events happen. I created this module for my personal assistant project on a Raspberry Pi (raspbian). The clap detection allows me to activate the assistant whenever I need it (and prevents it from continuously listening out for instructions or interpreting random noises as instructions)


This module works on linux based OS (raspbian, Ubuntu, Debian...) using alsa for audio and a working microphone or Mac OS X using coreaudio.


This module requires sox, "the Swiss Army knife of sound processing programs" (http://sox.sourceforge.net/) to be installed


sudo apt-get install sox

Mac OS X

brew install sox

npm install

You can simply add this module to your node.js project with

npm install --save clap-detector


First, create an instance of the ClapDetector class:

const clap = new ClapDetector()

Then register a callback that will be triggered whenever a series of hand claps is detected. Your callback will be provided with an array of claps and their associated timestamps as arguments.

const disposableOneClapListener = clap.addClapsListener(claps => {
  console.log("heard 1 clap", claps)
}{ number: 1, delay: 0 })

You can dispose (remove) a clap listener by calling the disposable method returned by addClapsListeners

disposableOneClapListener() // dispose the clap listener

Finally you can call the dispose() method when you want to stop all clap detection and free associated resources



  • Type : Function
  • Arguments: (callback [Function], options [Object])
list of options
Option Description Default value
number Number of claps 1
delay Period within the specified number of claps must be heard (ms) 1000
force If true, trigger callback every time even if a listener with a higher number is triggered false

Real life example

import ClapDetector from 'clap-detector'
const clap = new ClapDetector()
clap.addClapsListener(claps => {
  console.log("change tv channel")
}{ number: 1, delay: 0 })
clap.addClapsListener(claps => {
  console.log("turn tv on", claps)
}{ number: 2, delay: 1000 })
clap.addClapsListener(claps => {
  console.log("turn tv off", claps)
}{ number: 3, delay: 1000 })

Full example

import ClapDetector from 'clap-detector'
const clap = new ClapDetector()
const disposableOneClapListener = clap.addClapsListener(claps => {
  console.log("heard 1 clap (force)", claps)
}{ number: 1, delay: 0, force: true })
const disposableOneClapForceListener = clap.addClapsListener(claps => {
  console.log("heard 1 clap", claps)
}{ number: 1, delay: 1000 })
const disposableTwoClapsListener = clap.addClapsListener(claps => {
  console.log("heard 2 claps", claps)
}{ number: 2, delay: 1000 })
const disposableThreeClapsListener = clap.addClapsListener(claps => {
  console.log("heard 3 claps", claps)
}{ number: 3, delay: 1000 })
// Cancel some clap listeners
// Cancel alls claps listener but 2 claps after 10 seconds
setTimeout(() => {
  console.log("only listen to 2 claps now")
}, 10000)
// Dispose (stop sox process and listeners) after 30s
setTimeout(() => {
  console.log("dispose all listeners and free ressources")
}, 30000)


You can pass a configuration object and override the default values when you create an instance of the ClapDetector class. If you don't the following config will be used.

var CONFIG = {
  AUDIO_SOURCE: 'hw:1,0', // this is your microphone input. If you dont know it you can refer to this thread (http://www.voxforge.org/home/docs/faq/faq/linux-how-to-determine-your-audio-cards-or-usb-mics-maximum-sampling-rate)
  DETECTION_PERCENTAGE_START : '5%', // minimum noise percentage threshold necessary to start recording sound
  DETECTION_PERCENTAGE_END: '5%',  // minimum noise percentage threshold necessary to stop recording sound
  CLAP_AMPLITUDE_THRESHOLD: 0.7, // minimum amplitude threshold to be considered as clap
  CLAP_ENERGY_THRESHOLD: 0.3,  // maximum energy threshold to be considered as clap
  MAX_HISTORY_LENGTH: 10 // all claps are stored in history, this is its max length
const clap = new ClapDetector(config)

If you wish to improve the clap detection you can fiddle with the CLAP_AMPLITUDE_THRESHOLD and CLAP_ENERGY_THRESHOLD values. Depending on your microphone these might need to be modified.


These will be added soon. Please do not hesitate to submit some Ò!

About the Author

I am a full-stack Javascript developer based in Lyon, France.

Check out my website


clap-detector is dual licensed under the MIT license and GPL. For more information click here.


npm i clap-detector

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