Now that the iPhone 7 and the iPhone 7 Plus (well, technically) are on sale, we didn't have to wait too long to see the devices torn down to bits.

Naturally, we were especially interested in the part where the headphone jack used to reside on the same-sized iPhone 6S. Apple has taken a lot of flak for removing this part, so one would imagine there was a very good reason to do so.

If you look at the components within the chassis that reside where the headphone jack used to be, you'd probably think Apple didn't replace the headphone jack with much. The majority of the space previously occupied by the 3.5mm audio connector, and the accompanying electronics, is now taken by a simple piece of plastic.

The truth is more complicated than that, of course. Removing the headphone jack allowed the repositioning of many components and the expansion of others, according to what Apple engineers told Buzzfeed last week. This allowed, among other things, the addition of optical image stabilization to the iPhone 7 camera.

But what is that plastic piece, and why couldn't it have just been a headphone jack if Apple wasn't going to use that space anyway? Actually, Apple is using that space for a very specific reason. Since the iPhone 7 is now more of a sealed box because of its water resistance, Apple told Mashable the components in its place (including that piece of plastic) now function as a barometric vent to equalize the internal pressure to have an accurate altimeter.

(Turns out it's not for channelling sound from outside the phone into the microphone, as iFixit speculated.)

On the left, you can see the headphone jack's replacement in the iPhone 7 Plus. On the right, the headphone jack in the iPhone 6S Plus (it's the grey part in the bottom left). Image: iFixit

The vent has a secondary benefit: It also increases the dynamic range of the iPhone 7's stereo speakers. As any audiophile knows, strategically using vents is a key part of speaker design, and can often assist in augmenting sound on the low end. In other words, thanks to the vent, the iPhone now has better bass.

And yes, the Taptic Engine is now bigger. But bear in mind that the Taptic Engine in the iPhone 6S was actually significantly bigger than the one in the iPhone 6S Plus — indicating that Apple does have some room to play with that part's size without compromising functionality.

Is all that worth the removing the headphone jack? That's still up for debate, but, from what Apple has said, removing the jack meant its engineers were able to enhance many of the device's features and functions. Whether that constitutes "courage" or not is up to you.

Correction: While the addition of water resistance to the iPhone 7 necessitated the inclusion of the vent, the vent itself doesn't contribute to the device's water resistance as this report originally indicated.

Pete Pachal contributed to this report.

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