How can I add speech synthesis to a website like MakeUseOf search?
I assume you mean speech recognition? It's only supported in webkit browsers, but check out the source code, it's very easy to copy; add the following attributes to a text field, but be sure to adjust the onwebkitspeechchange to whatever JS action you want performed on completion.
onwebkitspeechchange="doSearch()" speech="true" x-webkit-speech="true"
If you are using Chrome you could try the extension Chrome Speak http://www.makeuseof.com/dir/chrome-speak-chrome-speak-websites/