Stereophonic sound uses two speakers to deliver two very different sound channels (depending on how the music was recorded) to deliver sound that approximates what we hear when we hear music live. It uses two channels, because we have two ears. The HomePod is a mono speaker. It uses a ring of seven tweeters to adjust the volume of the mono sound it sends out in an attempt to provide balanced sound anywhere in a room. It does not create any form of stereophonic sound reproduction.
I’m correcting a statement that Daniel Eran Dilger on AppleInsider posted in a rebuttal to my recent article about the HomePod. While I’m happy to disagree on some points, he makes the statement below about the HomePod not being a mono speaker, which is simply incorrect.
He also makes the bizarre claim that “it’s a mono speaker.” HomePod is not a mono speaker. A mono speaker is a single speaker that can only deliver a single channel of audio, resulting in its sound clearly appearing to come from one source. Stereophonic sound uses multiple speakers to deliver at least two slightly different sound channels to create a wider soundscape. HomePod is a stereo speaker. It uses a ring of seven tweeters to send out stereo sound that creates a wide, surrounding sense of stereophonic sound reproduction.
Also, “a mono speaker is a single speaker” is not correct. A mono speaker can have multiple “speakers” – aka drivers – such as a woofer, midrange, and tweeter. Or use one floor standing speaker, that may have four or five drivers, for mono sound. At a minimum, most – though not all – speakers that aren’t portable have two drivers, a woofer and a tweeter.
Apple sells the HomePod as having “room-filling sound.” But they never suggest that it’s stereo. It’s not hard to test it: put on I Saw Her Standing There, on The Beatles’ 1963 album Please, Please Me. Paul’s voice is on the right channel, and the main guitar and the drums are on the left. This was common practice in the early days of stereo.
Listen to that song on a single HomePod and you’ll quickly understand that it’s not stereo. The two channels are in a single stream, and you don’t hear the voice on one side and the guitar and drums on the other. It’s logical: how would the HomePod know where the listener is to know how to separate channels? This would be possible; they could have, say, an iPhone emit a tone that the HomePod could identify, but aside from that, it’s just guesswork. In fact, go to your favorite streaming service and find the stereo and mono versions of this song. Listen to both of them on the HomePod: skip back-and-forth from one track to another. With the exception of the fact that the mono version is a bit louder, you will note that the sound is exactly the same.
In addition, Mr Dilger seems to ignore that stereo sound requires separation. There are plenty of “stereo” speakers that aren’t really stereo, because their two speakers (generally two tweeters; a single woofer can be used in such cases) are too close together. So even if the HomePod was an actual stereo speaker, with different audio coming out of the left and right sides, it wouldn’t sound like stereo, because there would be no separation. You’d get a sort of spatial effect if you were far enough away, but only if there are walls close enough to the HomePod for the different channels to reflect off.
Discussing my presentation of two HomePods on either side of an iMac – it’s not just “someone on Reddit” who imagined this; a lot of people hoped they could do this – he says:
This is purely ridiculous, as one HomePod delivers far more than enough sound to be placed within an arm’s reach of a seated computer user. Placing one on either side of an iMac to deliver “stereo” is simply a dumb idea, based on the misconception that HomePod is a “mono speaker” and that a Mac user would need to have two of them.
So he’s suggesting that one put the HomePod in front of the iMac to get a stereo effect…?
I’m not looking to get into an argument, but sometimes there are facts that can’t be explained away by fanciful marketing.
Source: Editorial: After taking the premium tier, HomePod will expand in markets Amazon and Google can’t
One more thing. I think what is confusing people about this is what Apple says about the HomePod:
HomePod combines Apple-engineered audio technology and advanced software to set a new audio quality standard for a small speaker, delivering high-fidelity sound and a wide soundstage. Featuring a large, Apple-designed woofer for deep, clean bass, a custom array of seven beamforming tweeters that provide pure high frequency acoustics with incredible directional control and powerful technologies built right in, HomePod is able to preserve the richness and intent of the original recordings.
The section I have put in italics is what makes some people think that the HomePod is actually a sort-of-stereo device. All it is doing with this “incredible directional control” is compensating for the shape of the HomePod. Most speakers point in a specific direction; the HomePod is omnidirectional. What it does, using its microphones and multiple tweeters, is modulate the volume from each tweeter according to the proximity of walls or other objects in rooms. And, using time delays and reverb, it can create a more spacious sound from a single speaker than one that is just pointing in one direction.
Look at this still from Apple’s animation about the HomePod:
You can see that two of the mauve circles point forward, and are larger than the two smaller ones that seem to reflect off the back wall. With these multiple tweeters, the HomePod can produce sound that can develop resonance if it is timed correctly according to the distance of walls. The blue circles are the bass, which, perhaps, also has a bit of delay. What is deceptive in this photo is that there are two pairs of mauve circles, suggesting that it might be stereo. It’s not, but the volume of each tweeter is adjusted using the “incredible directional control.” Hence the spatial impression that can make music sound less flat.
However, this fails totally when the HomePod is in the center of the room, but, in that case, the HomePod is far superior to a directional speaker, because it can send music in all directions. I would guess there is probably not much difference in volume when the HomePod detects that it’s far from walls, because the goal there is to fill the room completely. This is, in fact, the ideal use case for a single HomePod: in a central location, with people in many positions around it. Set it up on a table in the middle of a room when you have a party.
Apple continues:
With two HomePod speakers set up as a stereo pair, this soundstage gets even wider, delivering room-filling sound that is more spacious than a traditional stereo pair from a speaker that’s just under 7-inches tall. Using spatial awareness to sense their location in the room, each HomePod automatically adjusts the audio to sound great wherever it is placed and sound great together, using an Apple-designed wireless peer-to-peer direct link to communicate with each other and play music completely in sync.
This suggests that the “spatial awareness” is used to control which tweeters send audio. The HomePod knows it’s, say, a foot from a wall, and can tell that the other HomePod is at a certain direction, allowing it to figure out which way is intended to be the front. This probably doesn’t work if you set two HomePods, say, at ends of a table in the center of a room.
Note: some of this is educated guesses, based on what Apple has said, and the way the device is constructed (ie, seven tweeters and six microphones). For more details about this, watch Phil Schiller presenting the HomePod in 2017. Of course, you need to take with a grain of salt what he says about things like “ambient audio, the backing vocals and reverb.”