OS X Yosemite: Hear your Mac speak text
If you have trouble reading text on your screen, you can have your Mac speak the text whenever you press a key or set of keys.
Choose Apple menu > System Preferences, click Dictation & Speech, then click Text to Speech.
Select the “Speak selected text when the key is pressed” checkbox.
By default, speaking is enabled when you press Option-Esc. To choose a different key, click Change Key, press one or more modifier keys (Command, Shift, Option, or Control) together with another key, then click OK.
To have your Mac start speaking, press the specified key. To stop the speaking, press the key again.
If text is selected when you press the key, the selected text is spoken. Otherwise, available text items in the current window are spoken; for example, if Mail is the current window, an email message is read.Note: If no text items are available, you hear a beep.
To turn off this feature, deselect the “Speak selected text when the key is pressed” checkbox in Dictation & Speech preferences.
You can also use VoiceOver, the spoken interface for OS X, to hear descriptions of every item on the screen and to control