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Comment by janniks | Hacker News Reader

I was recently trying to figure out whether the microphone is usable when using my notebook in clamshell-mode. Turns out Apple added a privacy/safety feature to all Apple silicon-based Mac notebooks and Intel-based Mac notebooks with the Apple T2 Security Chip. It will hardware disconnect the microphone when the lid is closed, based on the lid sensors.

Pretty cool safety feature!! Even though I'm sad I can't use my mic in clamshell mode

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In case you or anyone else needs to disable the MacBook screen and still use the mic, camera, keyboard, trackpad etc. I added a feature called BlackOut in my Lunar app that can do that (https://lunar.fyi/#blackout).

This allows "clamshell mode" without closing the lid. (although some people might want to close the lid for desk aesthetics, this feature is not for them)

On Apple Silicon with macOS Ventura the feature can really disconnect the screen by Command-clicking the power button: https://shots.panaitiu.com/x52NJxpR

There's also a write-up on how I reverse engineered this feature: https://alinpanaitiu.com/blog/turn-off-macbook-display-clams...

On older systems, BlackOut mimics a disconnect by setting the screen to 0 brightness and mirroring it to avoid windows getting trapped there.

haha, that was a really interesting writeup. It looked a lot like the process I end up following when I try to reverse engineer something

The whole way through I kept wondering "Wow, I wonder how he's going to tie this all together in the end!" .. and then I got to the end

This is incredible software. Thank you for linking to it. It has features I've long wished for in a laptop!

The microphone is located inside the left speaker grille anyways, so it would be terribly muffled in clamshell mode anyways.

Note this is in contrast to previous models where the microphone had a tiny hole on the left edge (next to USB-C ports) and it could be used in clamshell mode.

Which at first I thought felt like a downgrade... but the reality is that your laptop isn't usually in a good position for mic pickup when it's closed anyways -- people often keep it off to the side or something, under a monitor riser, etc. While the speaker grille location, being front-facing rather than side-facing, is far better for picking up voice when using the laptop normally. And that anybody using a mic in clamshell mode usually already has one in their webcam or AirPods or headset or a dedicated mic anyways.

So all in all it seems to work out pretty well.

Can confirm with my older MacBook that anytime I try to use the microphone with the lid closed people always complain.

I have leaned on the clamshell mode mic from time to time as well.

Tbh getting a simple but high quality mic has been nice.

It picked up a Steelseries Tusk.

It was the highest recording quality I could find for in ear headphone with a small boom mic for the dollar.

Easy to leave one each in my bag and desks if I like it. I’m considering finding a way to use the mic only.

It doesn’t hurt to be the clearest sounding person by a long shot on most calls.

https://www.amazon.com/SteelSeries-Tusq-Mobile-Gaming-Headse...

https://www.rtings.com/headphones/reviews/steelseries/tusq .. the recording quality section is of interest.

The 2015 pro model i have is an absolute nightmare for the fan as the mic was picking up the noise of the fan and so the CPU was working overtime to cancel the noise leading to cascading fan and heat noise.

Ended up just disabling it completely permanently. Was a particularly bad design i think.

I recently got an M2 Macbook Pro to replace my 2017 Macbook Pro (with that awful keyboard and the touch bar), and my biggest take away is that I'm glad Jony Ive left. The new one is less "elegant", but it approaches and in some case exceeds "functional". It's crazy the number he did on the hardware designs at the end.

> The microphone is located inside the left speaker grille anyways, so it would be terribly muffled in clamshell mode anyways

I don't think the hardware disable is meant as a UX convenience ("let's always disable it in clamshell mode because it sounds terrible"), as that could have just been done in software. It's meant for people privacy-conscious people who want to see a closed laptop and be able to assume it's not recording.

Meanwhile, I'm looking at this throwaway aside in the article:

> (The camera isn’t disconnected in hardware, because its field of view is completely obstructed with the lid closed.)

and thinking to myself that somebody is going to figure out how to record audio given just the "completely obstructed" view of the camera.

There's a long history of attackers reliably detecting logging keys with audio using just inter-keystroke latency and some histograms, or easily figuring out PINs tapped out on a phone screen because the OS doesn't bother putting access to accelerometers or gyroscopes behind an app permission. Attackers get very creative, especially when they're told that something is "impossible".

Recording sound from a video-only device that has been covered, with no hardware modifications would be a really really neat trick! Using Van Eck phreaking against all sorts of hardware is fascinating to me. FM radio broadcast from how RAM gets accessed and things like that. Maybe noise in the camera sensor can be used to pick up noise from the microphone on the motherboard (which is where the microphone is on Apple Silicon devices). I'm not going to say it's impossible, but it seems highly unlikely given everything else in play.

> There's a long history of attackers reliably detecting logging keys with audio using just inter-keystroke latency and some histograms

I wrote some fiction about this. The cosmic microwave background is hiding an audio signal. It's the sound of a keyswitch. Humanity uses the radio astronomy equivalent of these techniques to discover which keystroke caused the big bang.

>>"Apple silicon-based Mac"

What does "silicon-based" - mean? What other computer is not 'silicon-based'?

Is there a way to mechanize the HW detachment of microphone connections at will while using the machine open?

That would be great - if you had a physical switch on the side of machine, which physicall moves the mic wire a mm away from the contact.

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Weird thing - I put tape over my webcam at all times, unless in use, obv.

After some time I received a pop-up alert on windows 11 and it lasted briefly, and went away - but freaked me out: "You should unblock your webcam" or something to that effect, I dont have the exact wording - but it was an alert telling me to unblock visibility of my webcam - I think it may have mentioned something about UX reasons - but it happened so quick I missed all the wording.

Yeah - tape over your cams.

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It would be cool to have a phone case where is the case screen-facing-flap is closed, it pulls the wool over the eyes of the front-facing cams, so even in 'sleep' mode when the case is closed, the phones cams are all covered... but the mic is a different creature.

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Remember when NSA was intercepting cisco equipment to install HW back doors in devices shipped to 'enemy' states.

We have known forever about NSA HW backdoors...

but a case that can manipulate the HW MIC switchoff mechanism of a phone with such capability would be cool.

Else ; we need 100% trustworthy ability to disable our Spy-Pilots.

> >>"Apple silicon-based Mac" > What does "silicon-based" - mean? What other computer is not 'silicon-based'?

Read as (Apple silicon)-based.

Thank you. Wasn't aware.

"Apple Silicon" is the brand of processors.

https://en.wikipedia.org/wiki/Apple_silicon

Ah, thank you.

Silicon-based, not to be confused with those nice vintage germanium-based Apple products from the '60s.

And how are we supposed to trust Apple that this is in fact what's happening?

With a Framework laptop I have a hardware physical switch and I can actually open it up and see the PCB trace and verify that it disconnects the microphone.

At the point that you're opening up the laptop and chasing traces, you can do the same thing with Apple devices (with a bit more difficulty). It's not like they're made with rainbows and moonbeams. If you're at that level of paranoia (no judgement if it's justified or not) and have the skill to, just open up the Apple device and chase PCB traces. If you go down that route, iFixit's a good resource with lots of helpful pictures. (But still sometimes not enough.)

If it's in-chip, it won't be with PCB traces, it would be solid state inside the chip and you wouldn't be able to verify without inspecting the wafer, which is way outside my area of expertise. It doesn't sound like there's a mechanical relay that they are using for this.

There's also that if it's inside the chip, there is a risk that malicious software or buggy firmware can still enable it against your permission.

With a Framework laptop you can peel back the bezel and it's right there in plain sight. If the switch is in the off position it's a hard physical break to the microphone circuit. There is no possible software that can enable the microphone.

Nothing can beat a physical switch but even if it's solid state, unless it's in the CPU itself (it isn't) there still need to be traces in/on the PCB to bring the data from the microphone to the rest of the system, so just probe those traces when the lid is open vs closed. Or learn how to decap chips. There are some really awesome videos out there about that on YouTube!

More importantly though, Apple learned their lesson with the iSight which had a software-based activation LED. They assumed a random script kiddie wouldn't have the smarts to be able to hack the kext kernel module to turn the camera on without also turning the LED on. Unfortunately they learned about the Internet shortly thereafter where random script kiddies were able to get instructions on how to modify that kext, leading to some embarrassing moments, for some (possibly naked) high school teens, and for Apple.

Thats why the linked article is very careful to specifically mention that even having root and being able to manipulate kexts is not enough to silently use the microphone while closed.

https://news.ycombinator.com/item?id=35059224

I did just peel back the bezel on my Framework here. It looks like those hardware disconnects use some sort of blade that interrupts what I'm assuming to be an optical switch of some sort, one for the mic and one for the camera.

I would really like to know why this comment was down voted. It is a perfectly valid question with a rational explanation. Indeed, I was surprised to have needed to scroll down so far to find it, as it was the very first question that popped into my head as well.

People are willing to put their love of Apple products over their values for open and verifiable hardware.

One could say that, given the market share, that the vast majority people don't care a whit about open and verifiable hardware.

Agreed. But Framework does seem to prove there is _some_ interest. Regardless. I find it strange that people flock to Apple products when Microsoft clearly embraces open source in more ways than Apple.

A lot of my comments get downvoted these days. Sometimes the mods even side with the downvoters and ask me to stop. If they ban me, oh well, their loss.

I think this is nothing else than Apple being a difficult topic again.

Hardware physical switches are a gimmick feature - if you can’t trust your OS to that degree, then you surely have bigger problems than your microphone.

Of course I can never trust a closed source OS like MacOS.

Linux is a little better. But it's not just the OS. I might be in a Google Meet call where I have given microphone access, but can I trust the mute button? I'd rather have a physical mute.

Just use a headset or external mic. If you're in clamshell you're probably at your desk/home office so that's quite reasonable.

Also nice - if I'm WFH and one of my family walks in with some drama, I close the lid, go clamshell mode, and I am quite sure any corporate spyware isn't listening in.

I wish there were good quality webcams without microphones. My external microphone has a mute switch but my Streamcam mic is still available to any corporate spyware.

I wish the same. In the meantime, I like using these physical USB switches to easily disconnect my webcam when not in use: https://www.amazon.com/gp/product/B07X82661H

There don't seem to be any USB3 capable ones sadly. The webcam I use supports USB2 too, but image quality takes a noticeable dip.

Lid sensors? Why didn’t they just have a hinge that the wiring ran through that disconnects at a certain angle…

I assume clamshell mode would affect heat dissipation through the keyboard.

The correct solution would be to have a hardware kill switch for the microphone (and camera). This is exactly what Purism laptops offer.

Probably not in Apple’s “it just works” design philosophy. Also that’s another moving piece that can break.

I mean... it doesnt seem uncommon to have people dock a closed laptop so I would argue it doesnt "just work".

How would a microphone work with the lid closed anyways? It’d be muffled. If you’re docking your laptop closed, you’ve got an external webcam / mic if you need those inputs.

Why would I need to get mic if I have it in laptop? It makes very little sense to me.

So then you dock it with the lid open, in which case the mic and camera work fine and aren’t muffled…

For the same reason you might have other external peripherals. A laptop, realistically, can only fit something so decent inside of it. The 2020+ MacBooks do have surprisingly OK internal mics, but that's about all they are: OK.

Maybe I'm just an extra-big baby about it all. But what I find a little annoying with the COVID-era of work-from-home and distance learning is how few people seem to care about audio. Even as a teenager on TeamSpeak, rather than getting a more expensive graphics card or whatever, I spent my money on an SM7B. Now it is more important than ever.

Maybe this isn't reasonable, but I feel like if not for yourself, to prevent "sorry, can you repeat that?" moments, you kind of owe it to the people who have to listen to you. Like as an autistic person, hearing a dozen people's overlapping background static, tinny compressed audio, etc, it really, truly slowly drives me nuts. I can't deal with that level of auditory sensory stuff all day. If someone has a bad microphone, I want out of the call ASAP.

A Shure SM58 will last you a lifetime, fit on your desk, cost <$100, and no one will ever complain about sound again.

People don't know how bad they sound. It's as simple as that I think, there is no easy monitor functionality in Teams and friends like the preview image for camera, so there is no urgency.

The laptop microphone will pick up whatever noise is in the room. It's easier to filter out background noise with a microphone that is closer to your mouth.

Two+ tiny holes at the top of the lid facing upwards when the lid is open and at you when the lid is closed

The position of the mic on the newer laptops is unmuffled. It's actually a very high-quality signal that can't be muffled. The only way to quiet it is to "kill" it; disconnect it.

The same way it used to work, by putting the input on the external facing portion of the case. Or even better, have both so that it can optimize for the current clamshell mode.

This is a hardware kill switch, in the form of a (set of) transistors

Can it be reprogrammed?

No. It is bare logic.

Interesting. Note however that my comment was a reply to "I can't use my mic in clamshell mode". A normal kill switch would solve this.

A cool feature on laptops would be a jumper you could physically disconnect, and a tiny window (on say, the bottom of the laptop) to verify it hasn't been reconnected.

If you need a window on the case of your laptop to verify that your hardware hasn't been tampered with, you've got bigger problems.

You're against transparent technology?

When it comes to privacy, for the vast majority of users, sane defaults are better than requiring the user to take manual action.

Exactly!!!

This might seem like I am an Apple fanboy but I am not, I have plenty issues with Apple products but when it comes to Privacy Apple is the only company amongst the big tech we can trust.

Microsoft, Google, Facebook are all anti-privacy and just about using dar patterns to steal users info. It’s disgusting.

> when it comes to Privacy Apple is the only company amongst the big tech we can trust

No, it's not: https://news.ycombinator.com/item?id=34299433, https://news.ycombinator.com/item?id=26639261, https://news.ycombinator.com/item?id=26644216.

I wouldn't leap that far, I'm just talking about the lid switch on a laptop here.

It is still the correct solution. A sensible default doesn't conflict here, but hardware switched are the only solution where you can be entirely sure.

The problem is a separate switch leaves mainstream non-paranoid users unprotected, because it requires conscious activation by the user.

And anyway, a lid switch is a hardware switch. But most importantly, it activates passively during normal usage patterns.

No, that's not the "correct solution". It's another valid solution, with a different set of costs and benefits.

I'd rather have an LED on the same circuit as the microphone. If it's live, it has to send current through it. Easy to observe.

Even if it was configurable to disable either.

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