James, I think you may be confusing Active Noise Control with Active Sound Control. The latter comes (came?) as standard on F-Sport models and aims to simulate a sporty engine note (and gear changes) through the speakers. The sound is louder depending on whether you are in Eco, Normal, Sport, Sport + mode.
On the NX at least, it is activated via a wheel like switch by your left knee.
And I agree, it's a bit like the paddles, you play with it a few times and then forget about it.