Some asshat just recently scratched the paint off my fender, so I took it in together. I told them about the noise. Luckily, the test driver heard the noise, but didn't look much enthusiastic about fixing it. They gave me the same shait they did to you. Basically, "it's not that big of a problem", etc.
I was prepared, just like you, and I bought the same spectral pro app for my android!
Seems like we think alike.
I showed it to him and that the most dB's are near the glovebox. OK, he wrote it down and said he'd let me know. There were two huge spikes as 13kHz and 15kHz. Like very high, 5x higher than ambient engine noise, and that's on a logarithmic scale!
A week later, when the paintjob was finished, he called me and said everything is fine, but none of their techs could hear the noise, not even with some audio equipment. When they asked, Nissan denied there are any issues of this kind and refused warranty ECU exchange. So I said that it's a dealbreaker for me, because I cannot drive the car with this noise, which I really can't, because it drives me crazy and after about 2hrs of driving, my head really hurts. I guess those of us who have better hearing are **** out of luck. Nevertheless, the dealership guy seemed sympathetic to my problem and said he'll try to do some more and ask other people to try to analyze it. But who knows, he may be lying.
Now I'm waiting and hoping they'll fix it. If not, I'm gonna report it two more times and after that, I believe I can request a refund under warranty. It's some kind of a law here that when you report a problem under warranty 3 times and they don't fix it, you're entitled to get your money back. But they have to acknowledge it first! I also have a lawyer who says I may have some ear damage from prolonged exposure to these freq's, so if everything fails, I'm gonna get my ears checked out and if there's the slightest drop in sensitivity in that range, I'll have more ammo.
I wish you luck with your car too! Let's hope we'll both get what we want.