Text to Speech feature (known as Chromevox) is now standard on Chromebooks.
Click the 3 dots on the upper right side of Chrome.
Search for voice. Click Manage Accessibility features.
Choose enable ChromeVox (spoken feedback) by changing the slider at the far right. Choose Enable select-to-speak. This will allow you to Highlight the text that you want to have read to you.
To change the settings such as rate of speed, pitch and volume, Click Text-to-Speech voice settings.
Use the sliders next to rate/pitch/volume to adjust each feature. Rate is how quickly the words are read with Pitch being how high or low the voice sounds.