I present the IPA (International Phonetic Alphabet) TTS (text-to-speech) bookmarklet. (Source)
Bookmarklet: IPA TTS (drag to your bookmark bar)
How to use: select any text that contains IPA and click on the bookmarklet. Wait a second for the iframe at the bottom of the page to load.
Try these examples: /ˌɪntəˈnæʃnəl/, /ˌɪntɚˈnæʃnəl/