We are a small non-profit with a large mission, and while we hear the desire for read-aloud support, we are not currently able to offer it within our product.
However, we encourage you to experiment with the third-party web browser read-aloud extensions that are available, as they are advancing in their capabilities and may work for your needs.
We do not test with these extensions, so we cannot verify if they will work or not, but one highly-rated Google Chrome extension in the Chrome Web Store is Read Aloud: A Text to Speech Voice Reader.
As with any service, please make sure you are comfortable with this read-aloud extension's terms and privacy practices before using it.
If this browser extension suggestion isn’t what you’re looking for, we have one other read-aloud option for you to consider, which may be helpful for longer Khan Academy articles. If, instead, you are using a screen-reader with Khan Academy, see this article.
Finally, if you'd like to know how we, at Khan Academy, make our content more accessible, check out this article.