Aside from pressing play or using the hotkeys, there are other ways to activate the extension to read from text. First, check that you have the Read Selection icon setting activated.
Click on the NaturalReader icon next to Chrome's URL field to open the extension.
If it is in compressed view, click on the gear to open the settings.
If the Reading Bar is activated (at the bottom of the page), click on ☰ to open the settings.
Scroll down or select 'Read Selection' from the left menu.
When the 'Show Read Selection Icon' setting is turned on, you can select or highlight text then click on that icon to begin reading. By default, this will read only the text you selected.
In these settings, you can also select how many characters must be selected before the icon shows up. The options range from 10 characters to 100.
Under 'Read Selection Options', you can also have it so it only reads the text you highlighted or make it continue reading from the selected text to the end of the page.
You can also set up a hotkey setting to more easily toggle 'Show Read Selection Icon' on and off.
Read Selection from play button, hotkey, read selection icon: pros:
highlighting and auto-scroll
continue to read to page end when clicking the play button again when it finishes reading the selection
supports the read selection to page end option in the menu
supports Google Docs
sentences might not be read smoothly due to DOM manipulation for the above pros
Read Selection from context menu: pros:
sentences can be read properly almost always
no highlighting and auto-scroll
no support for continue to read to page end when clicking the play button again when it finishes reading the selection
no support for the read selection to page end option in the menu
no support in Google Docs
If you have the 'Show Read Selection Icon' setting turned off, you can still highlight the text, right-click, and select 'Read selection' as an alternative to pressing play or using the hotkeys unless you are using Google Docs.