Hissing noise from iPhone 7 plus. Does it exist on older models?

Brand new iPhone 7 plus have hissing noise. Websites have mixed reaction about it. But this made me look at the older iPhone (6 plus) and see if there is a hissing noise. And to my surprise, there is a slight noise. But in iPhone 7 plus, it sounded worse.

Apple support asked me to take the phone to the Apple store and they said if it cannot be repaired, they will replace it. Lets see. I will update the post after the store visit.

In the mean time please update your iPhone to iOS 10.0.2. The update fixes the following issues:

• Addresses and issue that could prevent headphone audio controls from temporarily not working
• Resolves an issue that caused Photos to quit for some users when turning on iCloud Photo Library
• Fixes and issue that prevented enabling some app extensions.

Update (9/24/2016): Swapped the phone for a new one. Noise is still there.