NoiseAddicts has a great hearing test to see what you can and can’t hear. It provides sounds from 8kHz up to 22 kHz. Don’t fret if you can’t hear anything beyond 15 kHz. It just means you’re most likely to be over the age of 25 and that’s normal.
I can’t even hear the 8kHz with my implant. I thought something was wrong with the volume, but I tested it by watch a video on YouTube and all was fine. My hearing just sucks.