strange humming sound coming from back of Galaxy Note 9.

[usersiEgk8NRR8]

I was holding my phone today and felt my middle and ring fingers tingling, like something was very gently vibrating. I put my ear to the back of the device, and noticed a humming sound coming from the back of the phone. Unless this phone has a cooling pump or fans, I don't have any idea what could be causing this.

Here's a recording of the sound (taken with microphone from another device): https://drive.google.com/file/d/1aAuv_iS-ZHZkGc6bAaOsEslDBmBeksDu/ 

Here's a picture of where the sound is coming from: 

[SamsungJoJo]

Do the symptoms still occur in safe mode?

Let's try putting the device in Safe mode to determine if there are external factors that cause this symptom. This step will temporarily disable all your third-party apps, but none of your personal data will be deleted. Your customization settings (Wallpaper, Themes, et cetera) will be reset to default once you exit this mode.

Please follow the steps below:

1. Turn the device off.

2. Press and hold the Power key past the model name screen.

3. When "SAMSUNG" appears on the screen, release the Power key.

4. Immediately after releasing the Power key, press and hold the Volume down key.

5. Continue to hold the Volume down key until the device finishes restarting.

6. Safe mode will display in the bottom left corner of the screen.

7. Release the Volume down key when you see Safe Mode.

8. To exit Safe Mode, restart your device.

Let us know how your device responds after performing this step!

[usersiEgk8NRR8 · Accepted solution]

I rebooted the phone, and the sound went away. I am still curious, however, as to what could have been causing the sound. It wasn't coming from the speakers, and was causing the back of the phone to vibrate in a way I have never experienced before.

Not knowing what caused it, I have no idea if it will ever happen again.