Since National 5, Higher and Advanced Higher courses have all now changed to move completely to external assessment, only National 4 retains the old mandatory unit requirements beyond summer 2019.
Understanding Music means what it says, with the understanding presumably key to why it got renamed from the old ‘Listening’ (which was never about just sitting back and listening!). But, like its predecessor, it still involves identifying musical concepts both aurally (the contexts for learning) and on paper (the music literacy content). We should also note the increased emphasis on analysis (rather than just recognition) at Higher and Advanced Higher. While the Course Assessment requirements tell you what’s required for an overall course award at all levels and are all you really need to know for Nat 5, Higher and Advanced Higher, Understanding Music (National 4) currently still requires you to ‘Recognise and identify music concepts and styles by’:
1.1 Identifying level-specific music concepts in excerpts of music
1.2 Identifying the social and cultural influences which have influenced the distinctive sounds of specific music styles
1.3 Identifying and recognising the meaning of music signs, symbols and terms
So the ‘understanding’ part’s pretty obvious… you need to understand. But, where this understanding is now demonstrated purely through the Listening Paper exam for Nat 5, Higher and Advanced Higher course awards (plus an analysis component in the Advanced Higher Assignment), the separate unit specification at Nat 4 still requires you to collect a range of supporting evidence.