How to use the @iiif/vocabulary.ExternalResourceType.SOUND function in @iiif/vocabulary

load: this._extensions[Extension.OSD]
        };

        this._extensionRegistry[ExternalResourceType.IMAGE] = {
            load: this._extensions[Extension.OSD]
        };

        this._extensionRegistry[ExternalResourceType.MOVING_IMAGE] = {
            load: this._extensions[Extension.MEDIAELEMENT]
        };

        this._extensionRegistry[ExternalResourceType.PHYSICAL_OBJECT] = {
            load: this._extensions[Extension.VIRTEX]
        };

        this._extensionRegistry[ExternalResourceType.SOUND] = {
            load: this._extensions[Extension.MEDIAELEMENT]
        };

        this._extensionRegistry[RenderingFormat.PDF] = {
            load: this._extensions[Extension.PDF]
        };

        // presentation 3

        this._extensionRegistry[MediaType.JPG] = {
            load: this._extensions[Extension.OSD]
        };

        this._extensionRegistry[MediaType.PDF] = {
            load: this._extensions[Extension.PDF]
        };

bookmark(): void {
        super.bookmark();

        const canvas: Canvas = this.extensions.helper.getCurrentCanvas();
        const bookmark: Bookmark = new Bookmark();

        bookmark.index = this.helper.canvasIndex;
        bookmark.label = LanguageMap.getValue(canvas.getLabel());
        bookmark.thumb = canvas.getProperty('thumbnail');
        bookmark.title = this.helper.getLabel();
        bookmark.trackingLabel = window.trackingLabel;

        if (this.isVideo()) {
            bookmark.type = ExternalResourceType.MOVING_IMAGE;
        } else {
            bookmark.type = ExternalResourceType.SOUND;
        }

        this.fire(BaseEvents.BOOKMARK, bookmark);
    }