First attempt didn't work.

gumble/gumble/event.go

@@ -94,6 +94,11 @@ type UserChangeEvent struct {
 	Type   UserChangeType
 	User   *User
 	Actor  *User
+	// SelfMute and SelfDeaf preserve the optional fields from the UserState
+	// packet. A nil pointer means the server did not include that state in
+	// this update.
+	SelfMute *bool
+	SelfDeaf *bool
 
 	String string
 }

gumble/gumble/handlers.go

@@ -752,12 +752,14 @@ func (c *Client) handleUserState(buffer []byte) error {
 			user.Suppressed = *packet.Suppress
 		}
 		if packet.SelfMute != nil {
+			event.SelfMute = packet.SelfMute
 			if *packet.SelfMute != user.SelfMuted {
 				event.Type |= UserChangeAudio
 			}
 			user.SelfMuted = *packet.SelfMute
 		}
 		if packet.SelfDeaf != nil {
+			event.SelfDeaf = packet.SelfDeaf
 			if *packet.SelfDeaf != user.SelfDeafened {
 				event.Type |= UserChangeAudio
 			}

gumble/gumble/handlers_regression_test.go

@@ -26,3 +26,46 @@ func TestUserStateUnknownChannelDoesNotDeadlock(t *testing.T) {
 		t.Fatal("volatile lock was left locked")
 	}
 }
+
+type userStateListener struct {
+	EventListener
+	event *UserChangeEvent
+}
+
+func (l *userStateListener) OnUserChange(event *UserChangeEvent) {
+	l.event = event
+}
+
+func TestUserStateEventPreservesSelfMuteAndDeafFields(t *testing.T) {
+	channel := &Channel{ID: 0, Users: make(Users)}
+	c := &Client{
+		Config:   NewConfig(),
+		Users:    make(Users),
+		Channels: Channels{0: channel},
+		state:    uint32(StateSynced),
+	}
+	user := c.Users.create(1)
+	user.Channel = channel
+	channel.Users[user.Session] = user
+	listener := &userStateListener{}
+	c.Config.Attach(listener)
+
+	session, selfMute, selfDeaf := uint32(1), true, false
+	data, err := proto.Marshal(&MumbleProto.UserState{
+		Session:  &session,
+		SelfMute: &selfMute,
+		SelfDeaf: &selfDeaf,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.handleUserState(data); err != nil {
+		t.Fatal(err)
+	}
+	if listener.event == nil || listener.event.SelfMute == nil || listener.event.SelfDeaf == nil {
+		t.Fatalf("self state fields were not preserved: %#v", listener.event)
+	}
+	if !*listener.event.SelfMute || *listener.event.SelfDeaf {
+		t.Fatalf("unexpected self state values: mute=%t deaf=%t", *listener.event.SelfMute, *listener.event.SelfDeaf)
+	}
+}