The Sudden Voice
macOS includes a highly robust suite of Accessibility features designed to help users navigate the operating system. One of these features is “Spoken Content” (formerly Speech or VoiceOver). While incredibly useful for the visually impaired, users sometimes accidentally activate a keyboard shortcut that triggers the system to start reading on-screen text aloud. This can be jarring if you accidentally hit the shortcut in a quiet office or library, suddenly causing a robotic voice to start narrating the contents of your private emails or the web page you are currently viewing at maximum volume.
Silencing the Narrator
To prevent accidental vocalizations and stop macOS from automatically speaking text when you hit a specific key combination, you must disable the spoken content shortcuts in the Accessibility settings.
Click the Apple logo in the extreme top-left corner of your screen and select System Settings. In the left-hand navigation sidebar, scroll down and click on Accessibility. In the main right-hand panel, look under the “Vision” section and click on Spoken Content. Look for the toggle switch labelled Speak selection. If the robotic voice has been interrupting you, this is likely turned on (the default shortcut is usually Option+Esc). Click the toggle to turn it Off. Additionally, if the system is narrating every alert box that pops up, check the toggle just below it labelled Speak announcements and ensure that is turned off as well.