How we built Pixel Buds Pro 2 for even better sound and comfort

For the last two years, my trusty Pixel Buds Pro have kept me motivated with crisp and bassy beats while I run, blocked out the noise of subways and streets and silenced the clickety-clack of my colleagues’ keyboards when I need to focus on writing one of these stories. And they’ve stayed put in my ears.

So, when we unveiled Pixel Buds Pro 2 at Made by Google this year, I was pumped — I had to have them — and also curious. How much could a device so small improve in a single generation?

It turns out: a lot.

I took my Pixel Buds Pro 2 out for their first ride, and the enhancements came as advertised. Twenty-seven percent smaller and 24% lighter than my former Buds, they sat comfortably in the ear, held firmly there by a new twist-to-adjust stabilizer even as I lumbered inelegantly around a Sydney Harbor running track. Screeching gulls and ferry horns were no match for the twice-as-strong Advanced Noise Cancellation (ANC) — all I could hear were crystal-clear pop gems.

How had the Buds come so far between generations? I decided to ask around.

“Building Pixel Buds Pro 2 was about removing the need for compromises,” says Pixel Buds Pro Product Manager Colin Billings. “It used to be that if you wanted a bud that was light, you had to have a bud with a shorter battery life. If you were athletic and wanted buds that would stay on, you needed clips. Here you have a bud that is comfortable, secure and delivers great sound and noise cancellation. All in one.”

Powering that no-compromise approach is a custom chip called the Tensor A1. “After we launched the first Pixel Buds Pro in 2022, we knew we wanted to push the boundaries of noise cancellation and audio quality, in a smaller package,” says Audio Technology Development Director Michael Pate. “Off-the-shelf solutions wouldn’t meet those needs, so we followed the strategy used for Pixel phones and developed our own engine.”

The Buds team collaborated with the Silicon team early, outlining their final performance goals — from the computational demands of ANC to power consumption targets — and the algorithms that would be involved in achieving them. From there, the Silicon team began designing the architecture of the chip, and after rounds of testing, prototyping and validating performance, sent their final design to be fabricated. It arrived with the Buds team in 2023 ready to unlock new possibilities.

Tensor A1 chips feature ultra low-latency audio processing engines, pivotal to pushing noise-canceling bandwidth higher. “In the previous generation, we were processing audio inputs at five or six times the speed of sound,” Michael says. “With these latest Buds, we’re processing at 90 times the speed of sound.” That means as a soundwave hits the outside microphone and journeys towards your eardrum, the new Buds can perform more processes more quickly along the way — isolating sounds, canceling them and even creating “anti-noise” for sound that leaks through the earbud, all before you can hear it.

And because Tensor A1 has multipath processing, the continuous work being done for ANC is separated from the processes driving what you’re actually listening to. (No wonder my running playlist sounded so good: It had its own dedicated highway lane to my eardrums.)

Of course, none of these enhancements would be worth much if the buds were uncomfortable to wear. Which is why the team took a meticulous approach to their design.

A user experience research (UXR) team scanned the ears of people of various ages and backgrounds to generate a representative sample of multi-dimensional scans. “We wanted to get smaller and more comfortable, so we looked at places where buds might push against the ear and where they might slot in more naturally, and designed for that,” says Frances Kwee, who leads Pixel Buds hardware engineering.

To help figure out fit, Googlers lent their ears to the UXR team for scanning and then for testing different prototypes. “Early in the design process, the UXR team sent people home with dummy pieces of plastic and asked them to do jumping jacks, go for runs and wear them for several hours, just to report back on how stable and comfortable they were,” Frances says.

The team ultimately landed on adding a stabilizer to the design. This new small fin on the side of the bud can be adjusted to suit your use: Twist it to fit snugly against the bottom of your ear when exercising, or twist the other way for a looser fit.

Testing for audio quality was more challenging. Everyone’s hearing is different, impacted by biology, our exposure to loud noises and more. What sounds good or clear to one person might not sound the same to another. For that reason, the team increased the number of Googler testers they used compared to other audio products and standardized surveys for more consistent data and to eliminate as much bias as possible.

“We learned a lot from Googlers,” Colin says. “Take transparency mode, for example, which uses microphones to collect sound from the outside environment and replicate it in your ear — like you’re listening to music but can hear your surroundings. We thought people would be very concerned with all aspects of that experience, including how their own voices sounded when they spoke. Our learnings showed us that users were much more concerned about sound artifacts like amplifying natural ambient sounds. Based on this, we shifted our near-term focus to tuning the experience for those factors and plan to focus on aspects like self-voice, which we believe will become more important in the future, later.”

For the team behind Pixel Buds Pro 2, the future of the line lies not just in making pop tunes sound great — and canceling out anything that might get in the way of that. The new buds are also the first to integrate Gemini, allowing you to ask for directions without unlocking your phone and to chat conversationally through Gemini Live.

“We work hard to understand our customers and know what they want, and each successor generation builds from that,” Colin says. “As we look forward, we’re thinking about how we can use sound to go beyond listening, to bring you even more helpful services from Google without touching another device.”

Consider me pumped.