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Where to Speak on Your iPhone 4

Here’s what I knew about the microphones in the iPhone 4 and 4S before I got the really big surprise I’m going to share with you in a moment.

The iPhone has two microphones and two speakers, one of each on the bottom and another pair on the top. The microphone on the bottom is the grille to the left of the dock connector port as you look at the front of the iPhone — the grille to the right of the port is a speaker. This makes it easy to speak into the bottom microphone during a call. When you hold the iPhone up to your ear, you’re listening through the other speaker, near the top of the front face of the iPhone; if, at the same time, you rotate the iPhone up at an angle so that the bottom left corner of the iPhone is near your mouth, your voice naturally goes into the bottom microphone. The same is true when you’re recording a voice memo, or talking to Siri.

The microphone on the top is a tiny hole next to the headphone port. When you hold the iPhone up to your ear and speak into the bottom microphone during a phone call, the top microphone is used to perform some noise cancellation trickery. Since the top microphone is much farther from your mouth than the bottom microphone, the device can assume that what it’s hearing through the top microphone is mostly background noise and that what it’s hearing through the bottom microphone is mostly your voice, and it can invert the noise input and mix that with the voice input to reduce the noise component and make your voice clearer.

And now for the surprise. When you take the iPhone away from your face during a call and put it into speakerphone mode (tap the Speaker button), the top microphone is the one that is now active. Did you know this? I sure didn’t.

This fact makes sense, when you think about it, because in speakerphone mode, the sound comes out the speaker at the bottom of the iPhone. Thus, the microphone at the bottom of the iPhone needs to be turned off; otherwise, it would pick up the sound of the remote caller emanating from that speaker and feed it back down the line. Instead, the top microphone is used, maintaining maximal distance between the sound output (the bottom of the iPhone) and the voice input (the top of the iPhone). No noise reduction is performed, because only one microphone is in use, and this makes sense as well: in speakerphone mode, the iPhone is sending the caller the sound of the entire surrounding environment. The same rule applies during a FaceTime call, because the same situation applies: a FaceTime call is, by definition, a speakerphone call. (The top microphone is also the one that’s active when recording video.)

I didn’t know all this, and so, ever since I got my iPhone 4, I had been holding the iPhone wrong during speakerphone mode: I was holding the top microphone pointed away from me, because I thought “the microphone” was the one at the bottom during a call. Now that I know about it, I hold the iPhone better, and people on the other end can hear me better. Also, I use speakerphone less, out of sympathy with my callers. When you speak into the bottom microphone, you’re using superior electronics, because the bottom microphone is a better microphone, and you’re using noise cancellation. So if you want your caller to have a good listening experience, you should hold the iPhone up to your ear or use a headset of some sort — don’t use speakerphone mode.

That’s about all I have to say on this topic. I learned something interesting and useful, and I felt many people might not be aware of it, so I’m sharing it with you. But I can’t resist also ranting briefly about why I didn’t know this simple and useful fact. I didn’t know about it because Apple didn’t tell me! It might be stated in some Knowledge Base article, but I didn’t discover it, because I didn’t know I needed to look for it (and now that I do know, I still haven’t found it). The place I looked was in that flimsy little booklet that comes with the iPhone (with the cute title “Finger Tips”), and nothing was said about it there. In fact, I stumbled upon this little nugget of knowledge by sheer accident, while I was watching, of all things, a technical developer video of a talk from WWDC 2011. If I weren’t a developer, and if I hadn’t happened to watch this particular video, I might never have found out this fact at all — though in the course of preparing this article I have found a few discussions of the same topic, based mostly on experimentation of the “Can you hear me now?” variety.

What bad thing would happen if Apple provided customers with decent instructions for using their hardware? None that I can see. But by persisting in the myth that everything about an iPhone is obvious and that no manual is needed, Apple certainly does its users a disservice. And it does itself a disservice too, because an informed public uses the device more efficiently and is happier with it.


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Comments about Where to Speak on Your iPhone 4
(Comments are closed.)

Anonymous  2012-03-21 08:24
Matt, thanks for sharing this very useful information about the iPhone 4's microphones and speakers.

I totally agree with your last paragraph. Apple needs to provide much better tutorials on how to use its products, as they used to do, back in the '80s and '90s.
Chris Jennings  2012-03-21 09:17
There actually is a 178 page iPhone User Guide, though it doesn't include this bit of info.
David K  2012-03-21 11:03
So the iPhone is biased towards right handers. When a right hander hold the phone to his/her right ear, the microphone is on top next to the mouth. When a left hander holds the phone to his/her left ear, the microphone is on the bottom, away from the mouth. Do I need to remember to hold the phone at a slight angle to bring the mic closer to my mouth?
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-21 11:07
Handedness seems like a red herring. I'm right handed but I hold the phone to my left ear with my left hand, and the article assumes that in the description of how to talk into the bottom microphone.
John Baxter  An apple icon for a Friend of TidBITS 2012-03-21 13:09
I'm (strongly) right handed. I've always held a phone in my left hand (always = 60+ years). That way I can take notes with my right hand--the one that knows how to dial and write. I've never understood how righties came to hold phones with their right hands, or lefties (like Leo LaPorte) with left hands.
David Cowell  2012-03-21 11:09
And when recording Voice Memos, the phone uses the BOTTOM microphone. The upper mic seemed to be inactive.
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-21 12:23
Voice Memos are like calls: the top microphone is used to help with noise cancellation, as explained in the article.
Richard Smith  2012-03-21 15:33
Another reason for not using speakphone unless you have to, when I (and a lot of people really) hold the phone in speakerphone mode, I tend to have a finger or 2 on the other end (by the sleep button), this means it's possible to accidentally cover the mic that is actually working, this is on top of talking into what it now turns out to be the wrong mic.

Very good article.
thanks for the info. but i dont get one thing. why doesnt the iPhone use the better-bottom-microphone when i shoot a video? or both microphones, so it could generate an artificial stereo sound for the 1080p videos? do someone know the logic to just use the microphone on the top?
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-21 16:57
My guess is that, since we've no idea where the real sound will be coming from (could be you, could be the baby you're looking at), we record the ambient sound - the environment - just like we do in a speakerphone situation.
Greg C  2012-03-21 17:04
The iPhone guide does say that the top microphone is used for FaceTime calls, but doesn't say explicitly that the same thing applies to speakerphone calls.

Matt's point is well taken. If the "top microphone" was instead labelled "FaceTime/speakerphone mic" then everything would be clearer.
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-22 18:39
Perhaps we're not looking at the same document. I find no mention whatever of the top microphone, in connection with FaceTime or anything else, in the document I would call the "iPhone Guide" (, except in an illustration that says there is one (but not what it is for). Can you be more specific?
Greg C  2012-03-23 19:34
I checked two versions of said user guide (both for iOS 4), and both had the reference. Then I downloaded the latest version at the link above (iOS 5.1 version) to see what the problem was and, lo and behold, the reference is not there. Also checked the User Guide from Safari on the iPhone, and it's not there either.

In the iOS 4 version, the reference was in the Phone chapter in the FaceTime section, and simply said "Video calls use the top microphone on iPhone." So there was no explicit mention of speakerphone calls, just FaceTime video calls. Half of the information is better than no information, I suppose. Why it was deleted from the iOS 5 version I don't know, because it strikes me as being absolutely fundamental information. So, it was there and has since been removed. That's actually worse than it not having been put in at all.

I wonder what reference there was, if any, in the User Guide before FaceTime came along. Probably none.
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-23 19:50
Wow, that's really interesting. Thanks for checking; I'm really glad I asked about this! I never thought of looking in the older guide.
Anonymous  2012-03-22 05:56
Another quirk: the 4s keeps all mics live when you plug in a mic earpiece. So the friction of the phone in your pocket distracts the call and causes annoyance on both ends.
Adam Engst  An apple icon for a TidBITS Staffer 2012-03-22 06:22
I don't think that's true generally - I keep my phone in my pocket while using Apple's earbud mic, and I've never noticed any extraneous noise. It's too early to call anyone to test, but I checked with the Voice Memos app, and no matter what I did to the iPhone's mics, including rubbing them and snapping my fingers near them, they didn't pick up any sound (it all went through the earbud mic).

Perhaps your earbud mic wasn't properly seated? Or, and I did make this mistake once, if you plug in non-mic earbuds, the iPhone's mics have to stay active, which means that you're hearing through the earbuds but speaking through the iPhone's mics (not sure which one) and the quality is indeed lousy.
Kevan Pegley  2012-03-23 04:15
I don't have an iPhone, 4 or otherwise. But I couldn't agree more with Matt's comments regarding Apple not providing instructions. I guess the only good thing about it is that it fosters a small industry to create such guides (led of course by the venerable TidBITS team).

Is Apple the most successful company in history that gives every impression of not listening to, or caring much about, its customers? Is the secret to making such superior products to rise above the masses and not be bogged down by lowest-common-denominator reactionary thinking? I wonder if any business school case study has considered this factor in Apple's staggering domination of the markets in which it operates.
Adam Engst  An apple icon for a TidBITS Staffer 2012-03-23 05:43
It's an interesting issue, since Apple very much does care about their customers, and they sweat details that are far smaller than most companies would. But that leads to a "when it's done, it's perfect" mentality that can be at odds with the real world, because it's not actually possible to make a product so perfect that it works perfectly in every imaginable situation. And that's when you need someone to tell you how to use it best. (Which is, as you say, why there's a role for us in the industry!)
Player16  2012-03-26 07:08
What about those with 'bumpers'. Is the mic covered or is there a little pin hole? - I have a 3g phone so I don't know.
Adam Engst  An apple icon for a TidBITS Staffer 2012-03-26 08:07
Hah! There are a lot of different cases and bumpers, but if any of them are covering the microphone holes, that would be, as my 13-year-old says, an epic fail.
Derek Boldander  2012-03-25 22:48
Is noise cancellation performed when the Apple Earphones with Remote and Mic is being used?
Vernon  2012-03-26 20:14
Thank you for Constructive Criticism.
A concern and objection that are supportive and, I reapeat, constructive.
Frans Moquette  2012-03-27 13:30
"When you take the iPhone away from your face during a call and put it into speakerphone mode (tap the Speaker button)"

You know, I'm still wondering why the iPhone doesn't go into speakerphone mode automagically when you take it from your ear and vice versa. There are enough sensors in the iPhone that can detect that and make using the phone a lot easier.
Adam Engst  An apple icon for a TidBITS Staffer 2012-03-27 13:53
Ironically, when Matt and I were testing some of this stuff, for a short while we thought that might in fact be happening - it seemed to once, but then we couldn't reproduce. I must have just grazed the Speaker button with my finger at some point.
Curtis Wilcox  An apple icon for a Friend of TidBITS 2012-03-28 11:54
Automatically going into speakerphone mode? Sounds like a recipe for trouble. Here's a scenario:
Joe (on iPhone): Bob, hang on a sec, let me check with Mary.
[Joe takes phone away from his face and covers the bottom of the phone with his hand to muffle the microphone]
Joe (to Mary): Bob and Alice want us to come over for dinner but I can't deal with his boring chatter so I'm going to say you've already prepared a special dinner, okay?
Bob (through iPhone speaker): Joe, you know I can hear you, right?
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-28 12:21
But that's a problem already, since covering the bottom doesn't cover the top, which is still listening. The more fool Joe for not knowing about the Mute button!
Richard McKay  2012-03-27 15:13
Is this not moot if using Bluetooth or BlueAnt?
Matt Neuburg  An apple icon for a TidBITS Staffer 2012-03-27 16:21
Indeed. Obviously if you're using a headset you're not speaking into *any* of the iPhone's microphones. Hence the advice in the article to use a headset.
Cindy Krueger  2012-04-06 13:47
Thank you for this tip. My iPhone experience so far has made me sad. I have had difficulty with almost every call. Hopefully this will help at least in part.