CNET’s headline reference to “a rare look inside Apple’s secret iPhone 16 camera labs” is somewhat hyperbolic, since there’s nothing secret about them: we’ve seen one of them a couple of times before.
But the piece does, all the same, provide an interesting look at some of the testing processes used during the development of a new iPhone …
Our first look at Apple’s anechoic chamber was back in 2018, when the company showed it off to The Loop, followed by a second one just a couple of months ago, when Apple shared photos in an AirPods news release.
CNET was shown some of the ways Apple tests the microphones used to record sound for iPhone videos, demonstrated with the iPhone 16.
There is an array of speakers (roughly two dozen) mounted on a pipe in the shape of an arc that goes from under the wire mesh floor to the ceiling of the chamber. The speakers play a series of chimes and engineers measure what the iPhone 16 Pro’s mics pick up. The phone, which is mounted on a stand atop a turnable base, rotates a few degrees clockwise and the chimes play again. This continues until the iPhone has rotated in a complete circle.
The result is a spherical sound profile for each mic made from the data recorded in that anechoic chamber. Apple takes these profiles and uses it as the foundation for spatial audio and other software that can reduce wind noise or make iPhone recorded audio act and sound like different kinds of microphones – think a lavalier mic or in-studio mic for a voiceover.
“We want to enable that [Audio Mix] feature as if you record it on a lapel mic,” Dave explained. “We use machine learning algorithms as well as our tuning chains to come up with that signature sound that you’re able to get even with lapel mics.”
Interestingly, while the primary judgement of the results is made by “the golden ear” of Apple acoustics lead Ruchir Dave, they also test the different mixes with ordinary iPhone users.
As opposed to just having one person with a good ear tune the iPhone’s audio, Apple has a number of testers take a perceptual audio test and then uses those results to calibrate what you hear played back on your iPhone. I even got to be one of these testers while I was there and ran through a portion of the experience […]
Apple uses comparative testing like this much in the same way an eye doctor might have you select between two different lenses in an eye test. Without something to compare the audio to, it’s more of a challenge to evaluate a recording. The results from the perceptual testing help influence how the different aspects of the iPhone 16 Pro’s audio works, including Audio Mix.
For video testing, Apple has what it calls a video verification lab – essentially a way to ensure the end result will still look good when viewed under many different real-world conditions.
“We use this theater to tune the video playback experiences so that when you play back these videos in a dark room, in an office environment or even under the sun, that you get the same perceptual experience you will get as if you’re watching a video in the theater,” Sean Yang, director of video engineering at Apple, told me.
The whole piece doesn’t share any deep secrets, but it’s still an interesting look at just how much care Apple takes to sweat the small stuff.
Photo: Apple
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