disable echo cancellation and noise suppression

analyze.js

@@ -6,7 +6,14 @@ function startPitchDetection(callback) {
   }
 
   // Request access to the microphone
-  navigator.mediaDevices.getUserMedia({ audio: true })
+  //navigator.mediaDevices.getUserMedia({ audio: true })
+	navigator.mediaDevices.getUserMedia({
+  audio: {
+    echoCancellation: false,
+    noiseSuppression: false,
+    autoGainControl: false
+  }
+})
     .then(stream => {
       // Create an audio context and an analyser node
       const audioContext = new (window.AudioContext || window.webkitAudioContext)();

app.js

@@ -76,7 +76,7 @@ maxInput.addEventListener('change', ()=>{
 })
 
 startPitchDetection((heardPitch)=>{
-	if(newTone) {
+	if(heardPitch !== -1 && newTone) {
 		const centsDifference = 1200 * Math.log2(heardPitch / newTone)
 		document.querySelector('#analyze-pitch input[type="range"]').value = centsDifference
 	}