ARIA attributes for reading different text than in the HTML document

In my HTML document I am using roman numbers (e.g.: MMXV = 2015).

Is there a way to inform screen readers to interpret certain text in another way (e.g.: roman numerals as "Two thousand and fifteen" instead of M-M-X-V)?

My guess was that there would be an ARIA attribute, but I cannot seem to find one. E.g.:

<time datetime="2015" aria-?="Two thousand and fifteen">MMXV</time>