Is there a Non Directional Beacon(NDB) morse code sound database?
Here’s a website that has some NDB sounds that can give you examples of what an NDB sounds like.

Basically each NDB transmits a one, two, or three letter identification. 

On the chart, you can tell what to listen to by looking at the dots and dashes next to the identifier. In the example below, Chualar is UAD

..-
.-
-..