Can not play subtitle file for audio file.

[LiveIsLive]

This is my code, It is work for video file, but can not display subtitle for audio file.

public partial class VideoTest : Window
{
    public VideoTest()
    {
        InitializeComponent();
        this.MediaElement.Open(new System.Uri(@"Test.mp3"));
    }

    private void MediaElement_MediaOpening(object sender, Unosquare.FFME.Common.MediaOpeningEventArgs e)
    {
        e.Options.SubtitlesSource = @"Subtitle.srt";
    }
}