The Arabic switch allows you to switch automatic to a non-arabic voice as soon as NVDA reads text in latin alphabet.
To enable it open the “Arabic Switch” command under the “Acapela TTS for NVDA” menu. In the dialog box that opens up select the “Enable” check-box and then in the “Choose a voice” list pick the voice that you want to use to read latin alphabet and click “OK”. At this point you will need to restart NVDA for the changes to take effect.
The Arabic switch only works when you have selected one of our Arabic voices as main voice for NVDA.