When bellSound changes, update the bellAudioElements src

Fixes #904

src/Terminal.ts

@@ -485,6 +485,7 @@ export class Terminal extends EventEmitter implements ITerminal, IInputHandlingT
         this.viewport.syncScrollArea();
         break;
       case 'tabStopWidth': this.setupStops(); break;
+      case 'bellSound': this.syncBellSound(); break;
       case 'bellStyle': this.preloadBellSound(); break;
     }
   }
@@ -2303,6 +2304,12 @@ export class Terminal extends EventEmitter implements ITerminal, IInputHandlingT
       this.helperContainer.removeChild(this.bellAudioElement);
     }
   }
+
+  private syncBellSound(): void {
+    if (this.soundBell() && this.bellAudioElement) {
+      this.bellAudioElement.setAttribute('src', this.options.bellSound);
+    }
+  }
 }
 
 /**

src/Types.ts

@@ -31,6 +31,7 @@ export type BooleanOption =
 export type StringOption =
     'cursorStyle' |
     'bellStyle' |
+    'bellSound' |
     'termName';
 export type StringArrayOption = 'colors';
 export type NumberOption =