As the title reads, i have a 2021 nx300 with 12k miles on it and I have been experiencing this very annoying sound coming from the radio section. It comes and goes randomly, mainly notice this after 10 minutes of driving and sometimes goes away after driving for an hour Plus. I have recorded a video of the noise, link below.

https://youtu.be/kMIXaN4Da54

 

Some people (such as myself) will be reluctant to click on an external link. So I am going to refrain from doing so, if I can.
What exactly do you mean when you say it is coming from the "radio section"? Is it a particular speaker? The area on the dash where the controls are?
Does the sound get louder with louder volume (and lower with lower volume)?
Is the sound only when you're using a specific SOURCE, or all SOURCEs? For instance, is the sound only there when you listen to AM? FM? Sirius/satellite? What about if you play a CD disc?
If the sound is from the radio, for instance, does the sound change in any way when you change stations?

Some other questions:
How long have you owned the NX for? How long after ownership did this strange 'sound' start?
Have you recently had any electrical work done?
What/when/where did you most recently have ANY work done on the NX?

From the onset, it sounds to me that it can be one of two things: 1) A bad/blown speaker, 2) A bad wire connection.
It sounds awfully strange that it starts after 10 minutes and goes away after an hour!

 

I hear a sound reminiscent of a sewing machine, followed by a series of clicks, after which the "sewing machine" noise stops. Which is the sound you find annoying (perhaps both)?
Do you have the F-Sport model with fake engine noise?

 

No I have the regular trim, the sound im experiencing sounds like electric current, a ZZZZZZZ sound.

 

When I say the radio I meant where you would put in a CD. The sound is like an electric current or a motor whine and it's not from the speakers. Changing the source or volume does not change the noise.

I have owned my 2021 NX for about a year now and I noticed it after only 3000 miles.
No electric work done, no modifications, all dealer maintenanced.

 

Tell us what happens when you turn your climate control completely OFF (no AC, no Defrosters, Fans OFF, also Seat Fans OFF, etc....).

 

With this new information, to me it sounds like a MECHANICAL problem, and not electrical. In other words, it could be the CD mechanism malfunctioning, or perhaps a blower/fan. Regardless, you're probably still under warranty.

Here's something you can try....put a CD in the reader and play it. Does the CD player WORK? Do you still experience that sound? If so, then that rules out the CD mechanism!

 

You may notice that sometimes driving by semi your radio will emit this type of noise. This is if truck electrical system has problem. So, there is a chance that this noise is induced by your car engine ignition system. E.g., faulty spark plug wire may do that. I understand this is long shot, but I would check wires and how tight spark plug coils are seated.