Q: What is the keyboard shortcut for changing dictation language in Yosemite?

As far as I know there isn't one.  Try

https://fouquet.me/apps/dictationswitcher/

Until the developer can release dictationswitcher compatible with Yosemite, here is an AppleScript that will toggle between two languages. After it switches, it will speak which language has been set. Currently, the spoken text is in English (United States). This script will work on Yosemite and Mavericks. Tested.

What you need to do to get this to work.

1. Add your alternative language to the Dictation Language pop-up.
   1. Set your languages in the AppleScript property strings exactly as they appear in the Dictation Language Menu.
2. Copy/Paste the following AppleScript into your Script Editor (/Applications/Utilities).
   1. Click the hammer (compile) button
   2. Save once as File format text (dictation.applescript) - don't hide the extension, or check any of the checkboxes.
   3. Option+Save As… File format Application to your Desktop. Hide the extension, and check no other checkboxes.

The first time that you run this application, you will receive a dialog box just like the one below (I changed the name back to dictation):

Click Open System Preferences. Click on the gold lock button in the lower left corner. The Accessibility category will be selected, but the dictation application in the list of apps will be unchecked. Check it, and then click the gold lock again. Quit out of the dictation application on your Desktop, and run it again. If you happen to get another dialog indicating that it still does not have permission, revisit the System Preferences > Security & Privacy panel, and under the Privacy tab > Accessibility, uncheck the dictation application, and then recheck it again. Quit System Preferences. This happened to me, and following this second action allowed it to work properly.

Future releases of OS X may impact this application if Apple changes the order of the UI elements.

I modified this AppleScript from an Apple StackExchange post by qegal in 2012.

Copy/Paste the following AppleScript into your Yosemite Script Editor per the above instructions.

property defaultLang : "English (United States)"

property altLang : "German (Germany)"

-- property altLang : "French (France)"

tell application "System Events" to set p to (path to frontmost application) as string

     tell application "System Preferences"

     activate

          reveal anchor "Dictation" of pane "com.apple.preference.speech"

     end tell

     tell application "System Events"

          tell process "System Preferences"

               tell pop up button 1 of tab group 1 of window "Dictation & Speech"

                    click

                    try

                         if (get value of attribute "AXValue") contains defaultLang then

                             click menu item altLang of menu 1

                             say "Dictation set to " & altLang

                         else if (get value of attribute "AXValue") contains altLang then

                            click menu item defaultLang of menu 1

                            say "Dictation set to " & defaultLang

                         end if

                   on error errmsg number errnbr

                         tell process "System Preferences" to if it is running then quit

                         display alert altLang & "not configured in Dictation Languages, please add." as critical giving up after 10

                   end try

               end tell

       end tell

end tell

quit application "System Preferences"

activate application p

Thanks for this, it works great. You may get an error message, though, because the script tries to work on "tab group 1" before the window renders it. If so, add, before the "tell pop up button 1..." line:

repeat until exists tab group 1 of window "Dictation & Speech"

  end repeat

Hi Ludwip, is there a way to expand this code to toggle between 3-5 languages in a dropdown menu or key shortcut through FastScripts ?

Thx