You can watch a video about Sounds here:
The Macmillan Sounds app comes in two versions: the Free and the "Premium" (£3.99 / $5.99). The free download offers basic sounds for British & American English phonetic symbols, while the paid-for version adds wordlists which can be supplemented or replaced plus various activities and inter-activities.
This can be used by students working on their own to improve their pronunciation, or in class to demonstrate the sounds of English and how words can be pronounced.
Further information on this and similar products can be found at the Language Bits blog.
Acknowledgment: Thanks to Saeed Al Mannai who brought this to my attention.