Apple HomePod: sound technology explained

Apple HomePod: sound technology explained
The HomePod is out and while it is not the first smart speaker - it comes years after Amazon's Echo and Google's Home - Apple claims that it has worked for six years to make the HomePod sound "amazing" using the innovative technology beamforming and it has over 200 patents to back it up.

Here is how Apple itself describes the new HomePod:

"HomePod is a powerful speaker that sounds amazing and adapts to wherever it’s playing. It’s the ultimate music authority"

The ultimate music authority. These are some strong words. So what is the mysterious technology that Apple uses to make this the ultimate music authority and how is the HomePod different from all the other smart speakers out there? Let's find out.

Inside the HomePod

While you usually associate great sound with big speakers, the HomePod is a speaker that measures just 6.8 inches high and 5.6 inches wide, bigger than the Google Home, but still clearly a very, very compact speaker. Obviously, it is not engineered just like any other speaker of its size. Inside, everything is carefully arranged and tightly packed to fit an innovative idea: "beamforming".

Before we look into that, though, let's look at what is inside the HomePod. While most speakers place the woofer, the larger part of the speaker that is responsible for boomy bass, on the bottom, the HomePod has its rather large 4-inch woofer on the top. Then, on the bottom, tightly packed are not one or two, but a whole seven tweeters, each of them equipped with its own amplifier. Making it all work together is a circuit board in the middle with the Apple A8 chip, the same on Apple used on the iPhone 6 and 6 Plus, but tuned to the needs of a speaker. Additionally, there are six microphones around the center of the HomePod for Siri and one in the middle that measures the location of the woofer.

Location awareness and Beamforming

Apple says that the HomePod automatically senses its position and tunes the sound to its location. Here is what this means: while other speakers require manual setup, the HomePod automatically senses its position and adjusts the output from each speaker accordingly. This is not done for stereo effect (for stereo sound, you would need to wait for the AirPlay 2 update coming later this year and you will need two HomePod speakers), it's done to eliminate excess sound.

The first thing the HomePod does is detect the rough shape of the room it's placed in. It measures how far away it is from walls by firing sound and measuring how much time it takes for the soundwave to reflect and come back to the speaker. The bass output from the top is important for this measurement that happens in two stages, the first one a more rough and a second one that is more refined after that.

Once it detects its position in a room, the HomePod separates sound output from its seven tweeters into three "beams". This separation is called beamforming. The main beam fires sound directly towards the open room - vocals and guitars sound directly at you - while the other two beams (ambient sounds) are reflected off the "back tweeters", the ones that sound against a wall.

To understand which part of a song is vocals and should sound directly at the listener and which one is ambient sound it compares the left and right channels of a song. This separation is what surround systems have traditionally been using.

While all of this is happening, a dedicated microphone inside the HomePod constantly measures the level of bass and controls it automatically to keep bass audible, but not overwhelming a song. As the speaker knows the position of the bass woofer, it can push it to the maximum distortion-free level.

All of this detection happens within just 10 seconds and is completely automatical. Whenever you move the HomePod it will automatically do the adjustment all over again, as an accelerometer inside the speaker detects when it's moved.

Final Words

The HomePod is not only a technologically advanced speaker that is surprisingly powerful for its size, it also has clear output with great bass that is not too overwhelming. Best of all, it all just works, without a complicated setup process and it automatically adjusts it sound even as you move the speaker around. While the HomePod has a lot of deficiencies as a voice assistant and some weird limitations, it is a pleasure to listen to.



1. boucha26

Posts: 50; Member since: Jul 01, 2015

its amazing....

3. worldpeace

Posts: 3135; Member since: Apr 15, 2016

Still a mono speaker

2. Martin_Cooper

Posts: 1774; Member since: Jul 30, 2013

Brilliant hardware and sound quality trapped with s**tty useless software and apple walls.

4. BullDozer

Posts: 159; Member since: Dec 18, 2015

These products are all about assistant capabilities and this fails to deliver it. Overpriced dumb-speaker.

8. monkeyb

Posts: 414; Member since: Jan 17, 2018

As a long time Apple customer. I have no issues with Siri on the HomePod just because Siri(iPhone) never worked properly for me anyways and I agree that Apple needs to put a lot of effort into it to make it as good as the google assistant. I sincerely hope the Shazam acquisition will give them necessary talent and tools to make it better. Having said this, I will not be buying the HomePod just because it does not have a line in port (Aux) or at least the ability to pair with other bluetooth devices. This one feature would push some/many people like myself to buy the speaker. The good thing is that as the hardware is supposedly excellent, all it would need for Apple to do is send a firmware update to give customers these features. (I know this is asking for a lot :))

10. sgodsell

Posts: 7573; Member since: Mar 16, 2013

At the end of the day it is still a mono speaker. There is a future update that will bring stereo sound support. But you will then have to buy two HomePods. Now you are talking $700. If you cannot find a better sounding system for that price, that can do more than Apples homepods. Then you clearly are not looking.

11. TechSceptic

Posts: 1156; Member since: Feb 05, 2018

This isn't exactly news in any way. B&O (Bang and Olufsen) has been doing this for quite some time now, and since B&O are products that are situated within Apple stores in Denmark, i wouldn't be surprised if Apple more or less just copied this whole concept of audio devices that adapt to the room that they're in. It definitely seem like that, since the Homepod itself is merely a copy of B&O design. This just seems like Apple copying B&O.

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