Below is a short summary and detailed review of this video written by FutureFactual:
Inside AirPods Pro: A CT Scan Reveals the Tiny Engineering Marvel
In this video, a CT scan of a second-generation AirPod Pro reveals how Apple-packed components—from a compact lithium‑ion battery to a state-of-the-art Bluetooth antenna and multiple microphones—work together inside a space only slightly larger than a fingertip. The host explains how tight battery packing boosts energy density, why the stem houses the antenna, and how MEMS microphones built on silicon enable high‑quality voice capture and smart noise cancellation. The tour also covers how acoustic meshes, vent design, and moisture protection balance sound quality with durability. It’s a revealing look at how modern consumer electronics achieve remarkable performance through precise engineering and advanced manufacturing.
CT Scan Insight: A Tour Inside AirPods Pro
This video uses volumetric CT data of a 2nd generation AirPod Pro to show how every component is arranged inside a micro-sized enclosure. We meet the core elements—the 182 mWh lithium‑ion battery, the Bluetooth chip, and the stack of sensors and speakers—that together deliver six hours of use per earbud and the ability to connect seamlessly with other devices. The host explains the beauty of packing efficiency: a battery built like a rolled scroll, with layers of cathode, electrolyte, and anode tightly compressed to maximize energy density while minimizing resistance. The discussion also points out how poor packing degrades performance, turning more energy into heat and accelerating wear.
"The battery is built like a rolled up scroll with layers of material wrapped tightly around each other." - Real Engineering
Battery Architecture and Energy Density
The narrative dives deeper into how a compact 3-gram battery can store enough energy for hours of listening. It explains the concept of energy density, how the electrolyte and electrode arrangement influences performance, and how temperature shifts or physical shocks can create dead zones in the battery or accelerate degradation. The video contrasts the AirPod battery with larger devices to illustrate how industry-leading manufacturing helps maximize capacity in a tiny form factor.
"A rolled-up scroll with layers of material wrapped tightly around each other" - Real Engineering
Stem Antenna and the Bluetooth Link
The CT scan reveals a 2 mm wide, 10 μm thick antenna embedded in the plastic stem, a design choice driven by the need to avoid head-induced signal loss. Rather than a flat PCB trace, the antenna is molded onto a specially engineered plastic that’s laser-engraved to form precise conductive channels, then copper- and gold-plated for durability. The stem’s placement keeps the antenna away from the head, improving reception while fitting into the AirPod’s slim profile.
"Frequency hopping helps Bluetooth devices avoid interference in the crowded 2.4 GHz spectrum" - Real Engineering
Microphones, MEMS Technology, and Noise Cancellation
The video explains the evolution from traditional electric mics to MEMS microphones built on silicon, which use capacitive sensing with a fixed and a movable plate to convert sound into electrical signals. The arrangement allows multiple microphones to perform beamforming and improve voice capture for calls. A third mic near the speaker area, plus an ear-canal mic for real-time feedback, enables effective noise cancellation through a live loop that compares intended sound with what’s heard in the ear. An accelerometer wakes the microphones for Siri when you speak, all while keeping power use low.
"This structure, known as a MEMS microphone, has two conductive plates spaced just a few millimetres apart" - Real Engineering
Acoustic Design and Moisture Protection
To deliver consistent sound in the Ear, the design uses pinna-inspired acoustic meshes and careful venting to manage how air moves in and out of the earpiece. The Herman target curve guides the equalization to emulate a natural listening profile, balancing bass, mids, and treble while accounting for ear canal resonances that vary between listeners. Hydrophobic meshes protect the mics and speakers from water and dust without compromising acoustics, allowing AirPods to stay durable in real-world conditions. The section highlights how engineers choreograph airflow, vent geometry, and acoustic damping to prevent unwanted resonances and maintain sound fidelity.
"The Herman target curve is a benchmark for what good sound generally feels like to most people using headphones" - Real Engineering