I’ve been using Bluesky a lot lately (I’m @rich.lafferty.ca there), and one of the conventions there, like on Mastodon, is that images should have alt text.1 I configure my account to require it so I don’t forget, especially on mobile.

But one challenge with alt text is that you don’t know what it will sound like to someone using speech-to-text, and while that’s not the only way people use alt text, it is one use case.

So here is how to enable on-demand selection reading in MacOS (tested on Sequoia and Sonoma):

  1. Open System Settings.
  2. Under “Accessibility”, choose “Spoken Content.”

Screenshot of System Settings, with “Accessiblity” and “Spoken Content”\nhighlighted in a red rectangle

  1. Enable “Speak Selection”. If you want to change the key binding from the default of Option+Esc, then hit the little (i) info icon.

Screenshot of System Settings, showing the Spoken Content section,\nwith red arrows pointing to the Speak Selection switch and to the info\nicon

Now, when you’re writing alt text, highlight your text and press your shortcut, and you’ll hear it read aloud. You might find that you need to make changes, like describing typography, in order to get it to sound like you mean.

For example, without the extra bit here, Spoken Content ignores the underscore:

A Twitter post by twitter user @foo_bar (at foo underscore bar)

Bonus tip: The default voices in MacOS are not great. I’m a big fan of the American Englsh “Siri (Voice 2)” for understandability, but you might have to download it first. I don’t know the “correct” way to find the place where you download voices, but this will do it:

  1. Search System Settings for “Voice”.
  2. Choose “Voice (Spoken Content). A modal dialog will immediately appear. Click the (i) icon beside the currrent voice.

Screenshot of System Settings, with a search for “Voice” and the\nmodal described above

  1. Search that list for “siri”, and click the “Download” link on the “Voice 2” line. (Or try some other voices and find one you like.) In my screenshot I’ve already downloaded it, but you get the idea.

Screenshot of System Settings, with the voice downloading modal showing.\nAn arrow points to where the download button would be on the Siri voice\n“Voice 2” under “American English”

  1. Once downloaded, click that line to choose that voice. You’ll see a checkmark like in the above screenshot. Click OK.

Happy reading-aloud!

  1. Someone recently pointed out that not everyone can easily add alt text to their images, so please don’t harangue people for not providing alt text. If I can find the post I’m thinking of I’ll link it here. ↩︎