Change Speech preferences for accessibility on Mac
On your Mac, use the Speech pane of Accessibility preferences to customize the system voice, be notified when an alert or app needs your attention, and set a shortcut to speak selected text.
To change these preferences, choose Apple menu 
> System Preferences, click Accessibility, then click Speech.
Option | Description |
|---|---|
System Voice | Choose a voice to speak text and alerts. |
Speaking Rate | Set the speed at which text is spoken. Click the Play button to hear sample spoken text. |
Enable announcements | Have your Mac announce and speak alerts. To customize, click Options, then select a voice, the phrase you want to hear (such as the app name or “Attention!”) before an alert is spoken, and how long your Mac waits before it speaks the alert. |
Speak selected text when the key is pressed | Have your Mac speak text that you selected when you press the specified key. To customize, click Change Key, then press the key combination you want to use. (For example, press the Option and Tab keys together to change to Option+Tab.) |
Speak items under the pointer | Have your Mac identify items under the pointer, either all the time or only when you use zoom. You can set whether to have your Mac wait a shorter or longer time before speaking. |