docs: function(id) {
              if (!Crafty.support.audio) return;
              var c;
              for (var i in this.channels) {
                  c = this.channels[i];
                  if ((!id && c.active) || c._is(id)) {
                      c.active = false;
                      c.obj.pause();
                  }
              }
              return;
          }