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+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test PannerNode produces output even when the even when the distance is from the listener is zero</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="webaudio.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+const BUF_SIZE = 1024;
+const sampleRate = 44100;
+var types = [
+  "equalpower",
+  "HRTF"
+]
+
+async function testMono(panningModel) {
+  var ac = new OfflineAudioContext(2, BUF_SIZE, sampleRate);
+
+  // A sine to be used to fill the buffers
+  function sine(t) {
+    return Math.sin(440 * 2 * Math.PI * t / ac.sampleRate);
+  }
+
+  var monoBuffer = ac.createBuffer(1, BUF_SIZE, ac.sampleRate);
+  for (var i = 0; i < BUF_SIZE; ++i) {
+    monoBuffer.getChannelData(0)[i] = sine(i);
+  }
+
+  var monoSource = ac.createBufferSource();
+  monoSource.buffer = monoBuffer;
+  monoSource.start(0);
+
+  var panner = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "linear",
+  });
+  monoSource.connect(panner);
+
+  var panner2 = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "inverse",
+  });
+  panner.connect(panner2);
+
+  var panner3 = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "exponential"
+  });
+  panner2.connect(panner3);
+
+  panner3.connect(ac.destination);
+
+  const buffer = await ac.startRendering();
+
+  if (panningModel == "equalpower") {
+    // Use the input buffer to compare the output. According to the spec,
+    // mono input at zero distance will apply gain = cos(0.5 * Math.PI / 2)
+    // https://webaudio.github.io/web-audio-api/#Spatialzation-equal-power-panning
+    const gain = Math.cos(0.5 * Math.PI / 2);
+    for (var i = 0; i < BUF_SIZE; ++i) {
+      monoBuffer.getChannelData(0)[i] = gain * monoBuffer.getChannelData(0)[i];
+    }
+    compareChannels(buffer.getChannelData(0), monoBuffer.getChannelData(0));
+  } else {
+    ok(!isChannelSilent(buffer.getChannelData(0)),
+       "mono panning: expect non-zero left channel");
+  }
+  // Check symmetry
+  compareChannels(buffer.getChannelData(0), buffer.getChannelData(1));
+}
+
+async function testStereo(panningModel) {
+  var ac = new OfflineAudioContext(2, BUF_SIZE, sampleRate);
+
+  // A sine to be used to fill the buffers
+  function sine(t) {
+    return Math.sin(440 * 2 * Math.PI * t / ac.sampleRate);
+  }
+
+  var stereoBuffer = ac.createBuffer(2, BUF_SIZE, ac.sampleRate);
+  for (var i = 0; i < BUF_SIZE; ++i) {
+    stereoBuffer.getChannelData(0)[i] = sine(i);
+    stereoBuffer.getChannelData(1)[i] = sine(i);
+  }
+
+  var stereoSource = ac.createBufferSource();
+  stereoSource.buffer = stereoBuffer;
+  stereoSource.start(0);
+
+  var panner = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "linear",
+  });
+  stereoSource.connect(panner);
+
+  var panner2 = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "inverse",
+  });
+  panner.connect(panner2);
+
+  var panner3 = new PannerNode(ac, {
+    panningModel,
+    distanceModel: "exponential",
+  });
+  panner2.connect(panner3);
+
+  panner3.connect(ac.destination);
+
+  const buffer = await ac.startRendering();
+  if (panningModel == "equalpower") {
+    compareBuffers(buffer, stereoBuffer);
+  } else {
+    ok(!isChannelSilent(buffer.getChannelData(0)),
+       "stereo panning: expect non-zero left channel");
+    // Check symmetry
+    compareChannels(buffer.getChannelData(0), buffer.getChannelData(1));
+  }
+}
+
+async function test(type) {
+  await promiseHRTFReady(sampleRate);
+  await testMono(type)
+  await testStereo(type);
+}
+
+add_task(async function() {
+  for (const panningModel of types) {
+    await test(panningModel);
+  }
+});
+
+</script>
+</pre>
+</body>
+</html>