Schema.org basically provides structuring of data for marking up of websites, but we can use same rules for structuring of metadata for our purpose instead of creating new set of specifications for structuring.
Schema.org provides variety of schema to give structure to the data, in variety of formats. one of the important format we can use for structuring of metadata is JSON-LD format
{
"@context": "https://schema.org",
"@type": "AudioObject",