diff --git a/client/robot/robot.js b/client/robot/robot.js
index fdfabff2a97bba6472482ba76e903f6c967fd089..bc8ca5b898afd2856fc3c4004c236a559d50605d 100644
--- a/client/robot/robot.js
+++ b/client/robot/robot.js
@@ -32,12 +32,18 @@ robot = {
   previousReco: [],
   recordedParticipantsWS: undefined,
   participantsMediaRecorders: {},
+  participantsStream: {},
   isDisconnected: false,
   intervalList: [],
-  speakerId : {},
+  speakerId: {},
+
 
   processAudio(stream, callback, interval) {
-    const mediaRecorder = new MediaRecorder(stream);
+    var options = {
+      video : false,
+      mimeType : 'audio/webm'
+    }
+    const mediaRecorder = new MediaRecorder(stream, options);
 
     mediaRecorder.ondataavailable = callback;
     mediaRecorder.start(interval);
@@ -92,18 +98,18 @@ robot = {
   },
 
   openSTTSocket() {
-    if(robot.recordedParticipantsWS === undefined){
+    if (robot.recordedParticipantsWS === undefined) {
       const ws = robotLib.stt.getTranscriptSocket(e => {
         console.log('> ' + e.text);
         robotLib.reco.send(
           {
             from: robot.room,
-            text: e.from + '\t' + e.until + '\t' + speakerId + '\t' + e.text
+            text: e.from + '\t' + e.until + '\t' + robot.speakerId + '\t' + e.text
           });
       });
       ws.addEventListener('error', e => {
         // Try to open new connection on error
-        console.error('STT ws for ' + easyrtcid + ' error. Trying to reopen');
+        console.error('STT ws for ' + robot.speakerId + ' error. Trying to reopen');
         console.error(e);
         robot.openSTTSocket();
       });
@@ -120,13 +126,45 @@ robot = {
     });
   },
 
-  audioGenerator(easyrtcid, e) {
-    speakerId = easyrtcid;
-    robot.recordedParticipantsWS.send(e.data);
+  activityVoiceDetection() {
+    const keyMap = Object.keys(robot.participantsStream)
+    
+    let selectedStream;
+    if (keyMap) {
+      for (let i = 0; i < keyMap.length; i++) {
+        console.log('easyrtcid keyList value', keyMap[i]);
+        selectedStream = robot.participantsStream[keyMap[i]].shift();
+        robot.speakerId = keyMap[i];
+      }
+    }
+   /*
+    var arrayBuffer;
+    var fileReader = new FileReader();
+    fileReader.onload = function() {
+        arrayBuffer = this.result;
+        var byteArray = new Int16Array(arrayBuffer);
+        for (var i = 0; i < byteArray.byteLength; i++) {
+          // do something with each byte in the array
+        }
+    };
+    fileReader.readAsArrayBuffer(blob);*/
+  
+    return selectedStream;
   },
 
+  audioGenerator(easyrtcid, e) {
+    robot.participantsStream[easyrtcid].push(e.data);
+
+    const selectedStream = robot.activityVoiceDetection();
+
+    robot.recordedParticipantsWS.send(selectedStream);
+  },
 
   recordParticipant(easyrtcid) {
+    if (robot.participantsStream[easyrtcid] === undefined) {
+      robot.participantsStream[easyrtcid] = [];
+    }
+
     robot.openSTTSocket();
     robot.getUserStream(easyrtcid);
   },
@@ -178,7 +216,7 @@ robot = {
       });
     };
 
-    robotController.onAttendeeRemove = (e, data) => {
+    robotController.onAttendeeRemove = e => {
       robot.checkDisconnect();
     };
 
diff --git a/package.json b/package.json
index a3e7db712a5d227ba5ee19b87667b2b0eb173a07..7945d5a0c81b25d15dff57d68a2d81f30573c483 100644
--- a/package.json
+++ b/package.json
@@ -13,8 +13,11 @@
     "webdriver-stop": "./bin/webdriver-stop"
   },
   "dependencies": {
+    "@ffmpeg-installer/ffmpeg": "^1.0.13",
+    "@ffprobe-installer/ffprobe": "^1.0.8",
     "body-parser": "^1.18.2",
     "express": "^4.16.2",
+    "fluent-ffmpeg": "^2.1.2",
     "mz": "2.6.0",
     "puppeteer": "0.12.0",
     "sockjs-client": "1.1.4",