diff --git a/source b/source
index 9155017c896..fd100c5b88d 100644
--- a/source
+++ b/source
@@ -40709,12 +40709,7 @@ interface <dfn interface>MediaError</dfn> {
   </div>
 
   <div algorithm>
-  <p>While the <span>direction of playback</span> is backwards, any corresponding audio must be
-  <span data-x="concept-media-muted">muted</span>. While the element's <code
-  data-x="dom-media-playbackRate">playbackRate</code> is so low or so high that the user agent
-  cannot play audio usefully, the corresponding audio must also be <span
-  data-x="concept-media-muted">muted</span>. If the element's <code
-  data-x="dom-media-playbackRate">playbackRate</code> is not 1.0 and <code
+  <p>If the element's <code data-x="dom-media-playbackRate">playbackRate</code> is not 1.0 and <code
   data-x="dom-media-preservesPitch">preservesPitch</code> is true, the user agent must apply pitch
   adjustment to preserve the original pitch of the audio. Otherwise, the user agent must speed up
   or slow down the audio without any pitch adjustment.</p>
@@ -43358,19 +43353,37 @@ red:89
   <code>DOMException</code> must be thrown instead.</p>
   </div>
 
-  <p>A <span>media element</span> can also be <dfn for="media element" data-x="concept-media-muted"
-  export>muted</dfn>. If anything is muting the element, then it is muted. (For example, when the
-  <span>direction of playback</span> is backwards, the element is muted.)</p>
+  <p>A <span>media element</span> is <dfn for="media element" data-x="concept-media-muted"
+  export>muted</dfn> if any of the following are true:</p>
+
+  <ul>
+   <li><p>Its <span data-x="concept-media-muted-state">muted state</span> is true.</p></li>
+
+   <li><p>Its <span data-x="concept-media-muted-state">muted state</span> is "<code
+   data-x="">default</code>" and it has a <code data-x="attr-media-muted">muted</code> content
+   attribute.</p></li>
+
+   <li><p>The <span>direction of playback</span> is backwards.</p></li>
+
+   <li><p>Its <code data-x="dom-media-playbackRate">playbackRate</code> is so low or so high that the
+   user agent cannot play audio usefully.</p></li>
+  </ul>
+
+  <p>Each <span>media element</span> has a <dfn data-x="concept-media-muted-state">muted
+  state</dfn>, which is either true, false, or "<code data-x="">default</code>"; it is initially "<code
+  data-x="">default</code>". User agents may set a <span>media element</span>'s <span
+  data-x="concept-media-muted-state">muted state</span> to true or false (e.g., remembering the last
+  set value across sessions, on a per-site basis or otherwise).</p>
+
+  <div algorithm>
+  <p>The <dfn attribute for="HTMLMediaElement"><code data-x="dom-media-muted">muted</code></dfn>
+  getter steps are to return true if this is <span
+  data-x="concept-media-muted">muted</span>; otherwise false.</p>
+  </div>
 
   <div algorithm>
-  <p>The <dfn attribute for="HTMLMediaElement"><code data-x="dom-media-muted">muted</code></dfn> IDL
-  attribute must return the value to which it was last set. When a <span>media element</span> is
-  created, if the element has a <code data-x="attr-media-muted">muted</code> content attribute
-  specified, then the <code data-x="dom-media-muted">muted</code> IDL attribute should be set to
-  true; otherwise, the user agents may set the value to the user's preferred value (e.g. remembering
-  the last set value across sessions, on a per-site basis or otherwise). While the <code
-  data-x="dom-media-muted">muted</code> IDL attribute is set to true, the <span>media element</span>
-  must be <span data-x="concept-media-muted">muted</span>.</p>
+  <p>The <code data-x="dom-media-muted">muted</code> setter steps are to set this's
+  <span data-x="concept-media-muted-state">muted state</span> to the given value.</p>
   </div>
 
   <div algorithm>
@@ -43398,8 +43411,7 @@ red:89
    <li><p>If the user agent's <span>volume locked</span> is true, then return the system
    volume.</p></li>
 
-   <li><p>If the element's audio output is <span data-x="concept-media-muted">muted</span>, then
-   return zero.</p></li>
+   <li><p>If the element is <span data-x="concept-media-muted">muted</span>, then return 0.</p></li>
 
    <li><p>Let <var>volume</var> be the <span data-x="concept-media-volume">playback
    volume</span> of the audio portions of the <span>media element</span>, in range 0.0 (silent) to
@@ -43416,20 +43428,18 @@ red:89
 
   <p>The <dfn element-attr for="audio,video"><code data-x="attr-media-muted">muted</code></dfn>
   content attribute on <span data-x="media element">media elements</span> is a <span>boolean
-  attribute</span> that controls the default state of the audio output of the <span>media
-  resource</span>, potentially overriding user preferences.</p>
+  attribute</span> that gives the default value for muting.</p>
 
-  <p class="note">This attribute has no dynamic effect (it only controls the default state of the
-  element).</p>
+  <p class="note">This attribute has no further effect once the <code
+  data-x="dom-media-muted">muted</code> setter has been invoked or the user indicated a
+  preference.</p>
 
   <div class="example">
-
    <p>This video (an advertisement) autoplays, but to avoid annoying users, it does so without
    sound, and allows the user to turn the sound on. The user agent can pause the video if it's
    unmuted without a user interaction.</p>
 
    <pre><code class="html">&lt;video src="adverts.cgi?kind=video" controls autoplay loop muted>&lt;/video></code></pre>
-
   </div>