(Pocket-lint) - Six years ago, Apple decided it was going to get into the speaker business for a second time. The first attempt, the iPod Hi-Fi, launched in 2006 to mixed reviews.

Although the iPod Hi-Fi's life was brief, Apple says it was successful. And let's face it, 2006 was a different time for music. It was a time of iPod speaker docks. A pre-iPhone, pre-music streaming world where we were happy to store our music locally rather than in the cloud.

Fast-forward 12 years and Apple is once again launching a speaker, the Apple HomePod.

This time though things are different; the company is prepared: the Cupertino-based company has amassed a huge team of engineers and audiophiles to ensure the HomePod is a speaker to be reckoned with.

Headed up by Kate Bergeron, vice president, Hardware Engineering and Gary Geaves, senior director of Audio Design and Engineering, Apple’s audio lab is located just outside its shiny new Apple Park headquarters. We were invited along to take a look. 

"We care deeply about music at Apple," says Phil Schiller, Apple's Senior Vice President Worldwide Marketing, who's joined us on our tour of Apple's audio lab to see where the HomePod started its journey.

"From iPod, to iTunes, to Apple Music, to the iPad, to the Siri remote on Apple TV, to HomePod and of course AirPods. The work for all of that from an audio perspective comes through here.

Through the years we've built a pretty amazing audio engineering team to be able to make products that not only are we really proud of but push the bounds of what could be done in the class of products we are making. Part of that is a resource like this so they can understand those products and how to tune them."

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That resource involves a range of different sized anechoic chambers - at least 12 that we count - to enable Apple to "remove the room" from testing so that Geaves and his team can cleanly test the speaker without interference. 

Some are merely boxes only big enough to fit the product, while others are cavernous, buried in the ground and floating on springs to stop all sound seeping in. 

"If you measure a loudspeaker in a regular room, a lot of the measurements get contaminated," explains Geaves, formerly of Bowers & Wilkins. "You can't really see what's going on with the speaker, so these rooms are essential to allow our engineers to really see what's going on."

We find ourselves standing on a metal mesh see-through floor in one of Apple's chambers. It's big, filled with huge foam wedges on all sides, including beneath us.

"The foam wedges are to absorb all the sound so there are no sound reflections from the wall. It's kind of like being in an infinite cave."

It's effectively a room within a room sitting on isolating springs to dampen the movement even more. Even the cabling coming into the room is suspended so it can be completely isolated from the outside. 

Standing in one is a surreal experience; you can almost hear the blood rushing through your veins.

The home of HomePod

"We built this chamber specifically for HomePod," Geaves continues. "These chambers are essential to see exactly what's going on. Many companies use anechoic chambers, maybe not with the same specifications.

"But in our case, it was very important to create our own because of the very tight control we wanted over the directional behaviour of HomePod and its ability to sense and adapt to its environment. We are really concerned about what is happening in every direction and the microphones as well."

But it's not just the chamber; as Geaves admits, many companies have these and over the years Pocket-lint has been to more than a handful.

For Geaves, the special "magic" here is the array of microphones they've added to test the HomePod and the bespoke software Apple has created to test the HomePod's capabilities.

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"We developed everything from scratch. There's an arc of microphones and an arc of speakers and a heavy-duty turntable that revolves the HomePod. It's all very carefully designed by computer simulation to ensure the rig was doing exactly what we wanted it to do. And what that does, is to allow us to get in a full sphere around the speaker to get a complete understanding of what is happening firstly with the speaker itself, but also the microphones."

How HomePod adjusts its own sound

The testing, which has been constant since the project began, has enabled Apple to tune the speaker to work in any environment and ensure it doesn’t make any buzzes or vibrations when it plays, even at loud volume.

The A8 processor, which incidentally is also found in the iPhone 6, is used to automatically sense the HomePod's location in a room, then analyse and adjust the audio depending on where it's placed. 

The microphone array in HomePod listens to the reflection of the music off neighbouring surfaces and senses if it is against a wall, on a bookshelf, or freestanding in a room.

When freestanding in a room, HomePod beams consistent 360-degree audio throughout the room. When against a wall or on a bookshelf, the A8 chip analyses the music and appropriately beams direct energy and centre vocals into the middle of the room, while reflecting the ambient reverb and backup vocals against the wall for dispersion in the room.

The end result is an incredibly wide soundstage with a feeling of spaciousness and depth. The entire process happens automatically and takes just seconds. Each time you move HomePod even slightly, it uses the built-in accelerometer to detect a change in its location and readapts to the environment.

Testing Siri with HomePod

It's that technology that has been refined in the second big chamber we go into in our tour of the audio lab. This one, instead of foam wedges, features a hard floor and wall panels that can be swapped out to change the acoustic value of them. It's more akin to a kitchen than the set of a sci-fi movie.

"This is one of the rooms we started doing a lot of the testing of Siri and specifically Siri on HomePod," says Geaves.

"Reverberation is a problem for speech recognition. This room has typical acoustics. The way we did that was to go to the homes of hundreds of Apple employees and measure [the] different rooms.

"Within each room we carried out thousands of measurements, so we could characterise the behaviour, and in particular how echoey the space sounds. We found out the average of those rooms and then tuned the acoustics of this room to match."

It's clear this testing paid off. The key takeaway from our HomePod review is that the HomePod speaker sounds amazing, while the capabilities of the microphone and its ability to hear voice commands equally impressive regardless of the noise going on around it.

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It's not just about the sound the device makes for you to enjoy the music, but the sound the device makes when it makes that music. Ideally you don't want any noise. That could be trying to silence a hard drive whirring or fan rattling in a laptop.

Geaves and Bergeron's task wasn't just to make a speaker that sounds good, but one that doesn't make any noise at all while it makes that noise.

Testing at -2 decibels

The final chamber we go into is designed specifically to test for buzzes and unwanted noise from the speaker itself. It's similar to the previous chambers we've been in, but the specifications have been taken up a notch, considerably.

"The chamber is built on a 28-tonne slab of cement around a 1ft thick. The chamber itself is made of metal panels that are a 1ft thick that weigh around 28 tonnes. Between the slab and the chamber there are 80 very robust isolating mounts to make sure trucks going by don't contaminate the measurements. What that all results in is a near silent space."

As a guide, a well-engineered recording studio would have acoustics measured at around 20 decibels. The threshold of human hearing is 0 decibels, and the chamber created by Apple has a measurement of -2 decibels.

"There are lots of unique and custom components in the HomePod," explains Bergeron. These range from specially designed tweeters that factor in everything from reducing component buzz to even the creation of a new textile to cover the speaker, are a direct result of Geaves’ audio and acoustic team work as the two departments collaborate together to create that "perfect sound".

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That constant testing meant Apple didn't have to solve problems after discovering them but could factor solving them into the design process before they happened.

Our tour comes to an end, but we have time for one last question. We're keen to know how much Geaves work has influenced the design and performance of the HomePod.

"It's about balancing a whole bunch of different features and technologies. Obviously audio and acoustics is essential to HomePod and that's one of the things we focused on and were adamant that had to be great. One of the challenges of product development, certainly towards the end is that everyone wants to hold the line for their technology.

"One of the unique things about Apple is that the teams do hold their lines and we do find the right solution in the end."

It's clear when listening to the HomePod that Greaves and his team didn't move an inch.

Check our our full HomePod review as well as the best HomePod alternatives

Writing by Stuart Miles.