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diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-biquadfilternode-interface/biquad-tail.html b/testing/web-platform/tests/webaudio/the-audio-api/the-biquadfilternode-interface/biquad-tail.html
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--- /dev/null
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-biquadfilternode-interface/biquad-tail.html
@@ -0,0 +1,71 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>
+      Test Biquad Tail Output
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="/webaudio/resources/audit-util.js"></script>
+    <script src="/webaudio/resources/audit.js"></script>
+  </head>
+  <body>
+    <script id="layout-test-code">
+      let audit = Audit.createTaskRunner();
+
+      // A high sample rate shows the issue more clearly.
+      let sampleRate = 192000;
+      // Some short duration because we don't need to run the test for very
+      // long.
+      let testDurationSec = 0.5;
+      let testDurationFrames = testDurationSec * sampleRate;
+
+      // Amplitude experimentally determined to give a biquad output close to 1.
+      // (No attempt was made to produce exactly 1; it's not needed.)
+      let sourceAmplitude = 100;
+
+      // The output of the biquad filter should not change by more than this
+      // much between output samples.  Threshold was determined experimentally.
+      let glitchThreshold = 0.012968;
+
+      // Test that a Biquad filter doesn't have it's output terminated because
+      // the input has gone away.  Generally, when a source node is finished, it
+      // disconnects itself from any downstream nodes.  This is the correct
+      // behavior.  Nodes that have no inputs (disconnected) are generally
+      // assumed to output zeroes.  This is also desired behavior.  However,
+      // biquad filters have memory so they should not suddenly output zeroes
+      // when the input is disconnected.  This test checks to see if the output
+      // doesn't suddenly change to zero.
+      audit.define(
+          {label: 'test', description: 'Biquad Tail Output'},
+          function(task, should) {
+            let context =
+                new OfflineAudioContext(1, testDurationFrames, sampleRate);
+
+            // Create an impulse source.
+            let buffer = context.createBuffer(1, 1, context.sampleRate);
+            buffer.getChannelData(0)[0] = sourceAmplitude;
+            let source = context.createBufferSource();
+            source.buffer = buffer;
+
+            // Create the biquad filter. It doesn't really matter what kind, so
+            // the default filter type and parameters is fine.  Connect the
+            // source to it.
+            let biquad = context.createBiquadFilter();
+            source.connect(biquad);
+            biquad.connect(context.destination);
+
+            source.start();
+
+            context.startRendering().then(function(result) {
+              // There should be no large discontinuities in the output
+              should(result.getChannelData(0), 'Biquad output')
+                  .notGlitch(glitchThreshold);
+              task.done();
+            })
+          });
+
+      audit.run();
+    </script>
+  </body>
+</html>