Macmillan have a pronunciation app for you to download. With the Sounds app you have phonetic sounds and example words.
Just tap on one of the phonetic symbols displayed in Adrian Underhill’s chart on your phone, and listen to the sound. You can also listen to example words by holding the button down. The example words appear at the top of the screen, so students can easily check the spelling.
You can download the free version from www.soundspronapp.com. The full version (£4) contains more exercises.
Let us know if you have tried it!