Coding appearing in post descriptions on Arras theme

When I insert an audio file near the top of a post in WordPress (Arras theme), the coding for the audio file is displayed on the post preview description as if it were regular text.

For example:

Good evening, and welcome to Lights Out! Tonight’s story: ‘The Fall o’ the House of Usher’ https://www.quass.com/blog/wp-content/uploads/2013/08/parody-

Is there a way I can mark up such audio inserts so that they are not included as text in the recent post preview descriptions displayed at the top of my blog?

Thanks!