Inside Apple’s HomePod Audio Lab

Apple didn’t build its audio products by choosing off-the-shelf components that any other company can use—it designed and built them from scratch. The testing for all its products happens in the company’s audio lab in Cupertino, Calif. Last week, they took me on a tour of the lab to show me what’s involved in making an audio product at Apple.

“This impacts all of the products, it’s not just about HomePod,” said Phil Schiller, Senior Vice President Worldwide Marketing. “It’s about speakers in iPhone, the quad speakers in iPad, what we put into Macs, microphone pick up, AirPods, and Siri and Apple TV. All of those products at one point in the development cycle came through here.”

In fact, products will make several trips to the audio labs. As prototypes are made and tested, they get sent back to the lab to be tested, tuned, and retested. This continues until they are satisfied with every aspect of how the audio performs.

Kate Bergeron, Apple’s Vice President, Hardware Engineering, said the HomePod project started six years ago—that gives an idea of how long Apple has been testing and working on that particular product.

“HomePod started by us asking a question: What would it mean if we decided to design a loud speaker where we could put it in any room, and that room wouldn’t affect the sound quality,” said Bergeron.

She said that when the project started, it was a very small, focused team. When they felt they had something compelling, they went to the executive team at Apple to present their idea. After HomePod got the go ahead, they moved into the next stage of development, which included a number of other teams inside Apple that would handle thermals, compute, power, wireless, and the different sensors found in HomePod.

I had a look at a HomePod that was taken apart and put on a table. Every aspect of the device was designed by Apple, specifically for the HomePod. Even the fabric mesh that covers HomePod was designed by the acoustic team in collaboration with other Apple teams to make sure it was acoustically transparent, but still met all of Apple’s other standards.

“We think we’ve built up the biggest acoustics and audio team on the planet,” said Gary Geaves, Apple’s Senior Director, Audio Design and Engineering. “We’ve drawn on many of the elite audio brands and universities to build a team that’s fantastic. The reason we wanted to build that team was certainly for HomePod, but to also to double-down on audio across all of Apple’s products.”

The audio team also has some of the best gear in the world to work with. Apple built an anechoic chamber specifically to build and test HomePod. The chamber is non-reflective and echo free, so it is a perfect environment for testing audio.

Apple’s custom anechoic chamber in Cupertino used to develop the beam-forming speaker array and high excursion woofer in HomePod

Apple’s anechoic chamber is a room, built within another room and set on isolating springs so vibrations from the outside are kept out of the testing environment. It’s also one of the largest anechoic chambers in the United States.

“Anechoic chambers are a standard tool for loud speaker development, but it is especially so for a product like HomePod where we were really interested in the directional behavior,” said Geaves. “Not only how it sounds in one direction, but all directions. That’s a critical component of why HomePod works like it does and enables the system to adapt to the environments the system is placed in.”

Another chamber was built to develop voice detection algorithms so Siri could hear you even in loud environments.

“We went out to hundreds of employees rooms and took thousands of measurements in each room,” Geaves. “That allowed us to characterize each of those acoustic spaces and come up with an average for all of those rooms in terms of reverberation.”

When applied to Siri, this testing allows it to pick up your voice when you dictate or ask it a question, while ignoring the background noise. For HomePod, it allows Siri to know when you’re talking to it, even when music is coming out of the speaker that Siri is attached to.

A small chamber in Apple’s Noise & Vibration lab used to detect unwanted noises during HomePod development.

The noise and vibration lab was set up years ago to work on unwanted noise from Macs. At the time, this lab was very focused on fan and hard drive noise, but over the years it has expanded into electronic noise as well.

The last chamber I saw was designed to listen specifically for electronic noise. For example, you don’t want HomePod to make any kind of noise when it’s plugged in, but not in use. If it was sitting on your night table, you wouldn’t want a hum or buzz coming from it.

Geaves said that the extent you have to isolate this chamber is even more important because you are listening for really small sounds.

An extremely quiet Noise & Vibration chamber in Apple’s sound lab in Cupertino used to measure the noise floor of HomePod.

The chamber itself sits on 28 tons of concrete. The panels are one foot thick which is another 27 tons of material, and there are 80 isolating mounts between the actual chamber and the concrete slab it sits on.

The chamber is designed to be -2 dBA, which is lower than the threshold of human hearing. This basically provides complete silence.

As you might expect, development of HomePod has led to advancements in other Apple products, as well. Geaves confirmed that when I asked him during the tour.

“There’s been certain catalysts in the development of HomePod that are feeding other products,” said Geaves. “That’s one of our advantages—we work on a bunch of different areas of audio.”

My time at Apple’s audio lab was really eye opening. I got a real sense for the tremendous lengths Apple will go to make sure their products are second to none.



  • saretzky

    Jim, this is really phenomenal – I was hoping to see a sneak peek into HomePod’s development as the launch got closer. Super stoked that you got to take the tour!

    • Morgan

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  • Shameer Mulji

    Awesome! You definitely deserve the tour of Apple’s audio lab

  • Dana Pellerin

    Fascinating. I work at a hospital and one of our older facilities had a dead room used for hearing tests. Probably nowhere near how dead Apple’s room is but still it was super weird walking into it, and after a few minutes you really just wanted to get out of there. LOL.

    • Alex Hon

      Does having been in that room change how you perceive Simon and Garfunkel’s The Sound of Silence?

  • tipoo2

    “Because the audio lab was built to test many products in addition to HomePod, Apple’s senior director of audio design and engineering, Gary Geaves, hinted that progress made on the speaker in the lab has led to advances in other, unnamed Apple devices. “There’s been certain catalysts in the development of HomePod that are feeding other products,” said Geaves. “That’s one of our advantages–we work on a bunch of different areas of audio.””

    Sound quality has been their secret success story in the last few years, the Macbooks right down to the 12″ are among the best in the industry. Even the 12″ was in the top 2% of devices tested on Notebookcheck. Then the iPad Pro with the quad speaker setup, and even the iPhones built in speakers are serviceable now.

    The Airpods are decent, but I hope Gen 2 really carries away sound quality like some of their other products recently have.

  • Chris Denny

    Jim, I’m sooo jealous! What an educational and fun trip that was. Looking forward to Friday and my HomePod delivery.

  • Tommy C

    So just how quiet was that quiet room compared to other recording studios you have been in?

    • frikova

      “The chamber is designed to be -2 dBA, which is lower than the threshold of human hearing. This basically provides complete silence.” That migth answer your question.

      • Tommy C

        I know what he wrote, that isn’t what I asked. I asked what it sounded like to him. I’ve never been in a room that quiet, and Jim’s a good writer, so I was curious how he might describe it compared to a typical studio setting, which I have been in and I presume he has been as well.

        • stsk

          While I can’t speak for Jim, and I haven’t been in that room, I’ve been in other anechoic chambers and a lot of studios. The most noteworthy difference is the eerie “deadness” of the space in an AC (anechoic chamber) vs a studio. In a studio there are still quite a few reflective surfaces, (floors, windows, mike stands etc.), so noise you make is reflected and you can “hear” the reflected sound – it’s relatively quiet compared to spaces in your usual experience, but it’s a matter of degree rather than an absolute. If you’re not moving or making noise a well-insulated studio can be very quiet, but as soon as you move or clear your throat or make any noise you can hear the subtle reflections off surfaces. An AC is just dead and that’s weird because there really aren’t analogues in daily life.

          • Tommy C

            I didn’t even think about the fact your own motions either won’t make sound or just sound totally different due to the lack of reflection. It’d be fun to experience that.

          • Max South

            Thanks.

            1. How fast people would go insane in such “dead” room?

            2. I am sure the CIA has used it as a torture as they use everything for that purpose. But were there reports/leaks about it?

          • stsk

            There is a bunch of hype included in the article to make it dramatic. Most of the “make you crazy” talk seems to be conflating sensory deprivation stuff e.g. from John Lilly in the 60’s and 70’s. https://www.amazon.com/Center-Cyclone-Autobiography-Inner-Space/dp/099858018X/ref=sr_1_1?ie=UTF8&qid=1518308538&sr=8-1&keywords=center+of+the+cyclone+john+lilly Being in an anechoic chamber won’t make a normal person “insane” in a reasonable lifetime. It’s more of a vague unease, but can also be pretty cool. Real sensory isolation, like in a float tank, is wonderfully relaxing and is something everyone should try. Just being in a really quiet room is not a big deal, but it’s a neat experience.

    • Grant Klassen

      This noise isolation room has an advantage over recording studios, it doesn’t need HVAC, because no one needs to work for an extended period of time in it. A really good recording studio, with HVAC on, will have noise levels below 15dBA. It’s very hard and almost not practical to get down below 10dBA, the slightest clothing rustle, human breathing, or equipment noise would be picked up. A great studio microphone like the $1000 AKG C414 has a noise floor fo 6dBA.

  • Aji Saputra Raka Siwi

    How about Beats Audio?

  • Chris Hedlund

    I want one of those floor stands for the Home Pod

    • Walt French

      Yes, the review mentioned a peak in the sound level—around 1500Hz IIRC—due to reflections off the table that were perhaps too close to compensate for correctly. But the iFixit teardown (hacksaw-apart, yikes!) doesn’t show a likely way to mount it on a stand. Especially here in earthquake country, I don’t envision putting it anywhere it could jump onto the floor with a slight bump.

  • Dave

    This is awesome! But I want bigger pictures. Any chance of linking higher res pictures somewhere?

  • Jon Hendry

    “The panels are one foot thick which is another 27 tons of material”

    Panels? No other mention of panels. I assume this doesn’t refer to the acoustic foam panels.