I brought the carbon monoxide detector downstairs to show my wife after finding it with Claude and she said "you look like a cat that's proudly showing me the mouse that it caught".

> My wife still tells this story to all her friends as one of my biggest life achievements. Everything I shipped, the companies I founded -- pales in comparison to finding a dead smoke alarm

Do you not feel this way about it yourself? I know I would.

Could you elaborate on how you converted the phase shift into a precise direction? Just a linear mapping? Or did you "hone in" by adjusting the stick until the phase shift disappeared, then proceed in that direction?

Hahaha amazing. Also cool to hear stories about headphones used as mics, I didn't think it would be sensitive enough for that.

I have almost the opposite story.

Many many many years ago, I was a wee IT manager. Sort of a weird company, I was too young to be much more than smart kid who can install / fix anything.

Anyways, worked a few years there, made some friends, had one CAD engineer who was an utter jerk. In hindsight, probably a bully, but at the time just a really irritating person.

So that was my first foray into small electronics… worked up a small breadboard with a 555, some source of randomness I don’t remember now, a piezo speaker, and a 9v battery. It would emit a short beep at random intervals between roughly 60 and 240 minutes.

Stashed it above the ceiling tiles in his office on my last day at the company.

My version of this story is coming back from turbulent red eye to this type of beeping, spending an hour walking around trying to figure it out it by ear, eventually giving up as it always seems to be somewhere else.

It wasn’t until the next day did I realize that it was two separate locations!

> above the ceiling tiles

So I may in the future be the villain in a story like this if I am forgetful when I sell my apartment.

My upstairs neighbor is a moron who has flooded their apartment at least twice, so I have stashed moisture sensors into the access panels in multiple rooms as a sort of early warning system.

omg, I suppose the "old fashioned" way of just finding the period then anticipating it in different spots wasn't enough this time? :)

This is very humanizing. I like that.

Nicely done!

> Claude doesn’t have native audio input (yet), but it can run JavaScript and Python code that can analyze audio captured by a microphone.

LLMs can also do that with non-mic audio, btw. I had GLM (or was it qwen?) answer the question of "Why does the spotify version of the Metal Gear Rising" soundtrack sound so bad" - to great results.

Compared with the CD rips on archive.org, the noise floor was 27dB (!!!) higher, and, the whole thing was 10dB more compressed.

I cannot vouch for these specific numbers, but subtracting the good version from the bad one gave me a horrible delta wav file with lots to listen to, so there was definitely a _lot_ of difference.

It got the job done is what I want to say.

> I didn't mention this in the article, but this isn't the first time my family has been driven almost spare by a mysterious, hard-to-track beep.

https://xkcd.com/3100/

> Our dog goes outside and hides in the lavender bush if a smoke alarm starts making a "I need a battery" noise.

Our three dogs are absolutely terrified of the Nest smoke alarm after I almost burned down my kitchen trying to make some copycat crunchwraps a few years ago. =P They're so afraid of the smoke alarm that the monthly "sound check" thing Nest performs makes them quiver and quake. We used to be able to delay the sound check through the Nest app, so we could have a chance to bring the dogs outside before it goes off, but Nest seems to have removed that functionality.

The fun part about apartment living is the weird noise can be coming from a neighboring apartment you do not have access to or control to fix.

Pff that sound is horrible, and sorta hard to locate (because of the pitch?). Anyway. None of my neighbours seem to care and in summer I used to hear an orchestra of beeps every 5 seconds. It was maddening, I was contemplating of buying 1000 batteries, print a manual and shoving it in peoples mailboxes, although somehow I think it wouldnt have made a difference. I moved out eventually (not because of the beeps)

Next step isto make an iphone app and robotic arm that throws it and catches it and uses the spinning motion of the phone to triangulate.

Then its solved.

I did roughly that to find my mum's missing hearing aid the other day. The bluetooth would locate which room it was in but not much more detailed than that. It was stuck to some orange peel in a recycling bin.

It's O(logn) but you haven't accounted for how heavy each item in the array of n is.

  - the boxes are stacked
  - the heavy boxes are at the bottom of a stack, and you can't stack a heavy box on top of a light one
  - boxes aren't the same size
  - some boxes are open, so must be put on top
  - storage space and height are limited

In terms of physical effort taken it’s O(n). Move half, then a quarter, then one eighth, etc.

The number of partitions doesn’t matter either, the most straightforward case is the beeping box always being in the original room, so regardless of strategy you move n-1 boxes to narrow it down, and by symmetry it doesn’t matter which room beeps.

Or you could use a very heavy blanked to just cover some boxes to supress the sound enough to simulate moving boxes.

You are moving n/2 objects log(n) times, so its O(n.log(n))

Never ignore the constant factor.

Yes, but that's also O(log n) physical effort. This one's O(1) sitting on your butt.

(Out of curiosity: I think "physical binary search" is more properly O(n^{1/3} log(n)), or maybe O(n^{1/2} log(n)). Since physical objects have sizes, and moving things (or moving between things) takes time proportional to distance).

You just look in the last box first, duh.

That requires you to stand in the room and listen for which side. So it’s nlogn times a very long time constant

That was my proposed solution to finding something just today; it didn’t work, but one of the bags ended up containing an old contract from General Development Company. Apparently a late family member had been buying some land down there through them, but county appraisers showed that the land never changed hands until after GDC’s bankruptcy. Not even their kid had heard about this, so it really makes me wonder what the story was behind that considering they lived in the Midwest (but did have some relatives nearby in Florida).

> Move half the boxes to another room.

Alternatively, no.

You could also solve it by getting rid of the boxes of stuff you clearly don't need (if you needed it, it wouldn't still be in a box). The best way to solve a problem is to make the problem go away.

I love the idea of accidentally triggering this system.

You're trying to catch a fly that's been tormenting you. You clap your hands together to catch it, but it slips out. The motors on the spotlight whir. "No no no, cancel cancel!" It's too late. Your hunt now has an audience. The spotlight is on you. Your classmates are calling out when they see the fly, cheering your swats, and groaning when you miss. Even the professor is silently praying for your victory so they might be able to regain some semblance of control over the class.

I think it was "I've lost a server"

Edit: good ol 5273

https://bash-org-archive.com/?5273

This is the problem with technology. Some people just want to use it, so it's quite hard to tell whether this is really a quality of life improvement, or if it's just exciting for some weirdo (any programmer counts as weirdo here).

I've personally had to track down a beep before and used a similar technique as you suggest: time the beeps then be in right place to perform a kind of binary search to home in on it. I found a smoke alarm in the roof space above my flat, nailed to the top of the rafters that had been there since the building was built 20 years prior. It was annoying but I'm sure it took way less time and effort than "getting AI to do it".

It's still a bit surprising the first time. Especially if you've been playing with these things for years now almost exclusively with text and perhaps checking for extra fingers now and then.

I didn't have birdnet to hand and wanted to identify something. It was hard to take a picture with my phone but easy to record. Turns out one of the models was able to identify it.

I guess the Americans might appreciate gunshot identification and localisation or someone might drive around in winter/summer recording the streets to listen for heat pumps that are on the way out so they can advertise repair services. I would like a local version for movement/presence detection based on footsteps as an alternative to having pir sensors all over the place for my hall lights.

Hahahaha. You should slow down when you read

"The system worked as intended. It gave me the position of the beep to within about 40cm, then I dug through that specific pile of boxes and found an ancient carbon monoxide detector that desperately wanted its batteries replaced."

Something about:processes in Firefox, but displays sound playing.

In fact about:processes is a good enough replacement: just sort by CPU usage descending and you'll find the source in the top 5.

If you have an array of microphones all connected to a single device (so they share a sampling clock), and you know where in space every microphone is, this is a relatively solved problem. There are commercial "sound cameras" that have a panel covered in microphones to determine the angle the sound waves come in from.

I really like the idea of sound as automatic maintenance issue detection for cars. You could correlate repetitive noises with wheel speed or engine speed to help narrow down the subsystems involved, or even which cylinder is firing when a sound happens. Even one or two microphones would be helpful. You'd need to be careful not to accidentally record conversations inside the car and leak them to any maintenance tech, though.

Sound location is slightly different from sound identification. Is the noise constant or intermittent? Could be a clothes washer or drier, could be a sound system, could be pipes and water, could be sound transfer along a surface.

You can also build one pretty cheaply and simply with the miniDSP UMA 16: https://www.minidsp.com/products/usb-audio-interface/uma-16-...

https://www.minidsp.com/applications/usb-mic-array/acoustic-...

Oh, was gonna post a comment about this, I actually bought just last week their USBc version (Fotric Sonic 3), on eBay, for around $700. Works quite well, it has 64 mic array, I think it would be tough to replicate it to this level.

Lmk if anyone has any questions about it! It’s android-only, but I’ve gotten an agent to write a Mac version of it though haven’t tested yet.

eBay link to what I bought: https://www.ebay.com/itm/960060893216

It seems what happened with thermal cameras many years ago might be happening with acoustic ones now. They used to cost a lot more than that.

Great thing for tool checkout/rental at a makerspace!

Does it work for infrequent sounds? The sound might for example come in the middle of the night for two seconds, loud enough to wake one up, then go away. If I leave it on, can it do continuous recording and max or threshold-based capture?

> I tried recording it with my phone, but it doesn't pick anything up.

Doesn't pick anything or doesn't pick anything that you can hear back? Might still be worth giving for processing to an LLM as some nerd is able to locate a webcam location from the recorded sound and date [1].

[1] https://www.youtube.com/shorts/4CEHH2WyRKs

Phone mics are really frustrating. Haven't improved since the Nokia era as far as I can tell, but everyone's obsessed with camera quality. They're now better than human eyes while recording neighbours' music at 2am is often completely inaudible on the recording. My ears are like a 60-year-old's after some infections as a child (I'm fun at parties, not understanding anyone), yet I can understand the words in the song at that volume level

If anyone has recommendations for a small USB or Bluetooth mic (since my new phone—that I'll definitely start using, any day now for sure—has no headphone jack anymore), let me know. Not looking for a giant streamer mic, the less space it takes in my electronics box the better

You joke, but birds' alarm calls are usually fairly spectrally simple for exactly this reason: simple monotone sounds (or those with a very gradual frequency slide) with soft edges are hard for predators to locate while still communicating meaning to other prey animals.

On the other hand, warning calls are often spectrally complex. Think of a cat's hiss: it's nearly white noise, one of the easiest sounds to locate. By telling another animal exactly where you are, you project your confidence that you're able to win a fight.

Thanks, Vetinaris clockmaker.

You can time the envelope of the ramp, though

Yeah, I wouldn't do this for code that I was expecting anyone else to review.

This is actually the first time I've told an agent to write out a "problems.md" document - it was an experiment to see if stating the problem provided decent results, as opposed to working directly on a spec.

It did seem to work well though. I was outsourcing as much judgement as possible to the model, and the model did a good job at making decisions that got me to my required end result.

In this case, the AI could do the reasoning for me. Opus 5.5 and Fable 5.2 are really good!

> In fact (or IMO?), this "problems.md" document is entirely unnecessary. In many cases, simply describing the issue and providing the relevant context is enough for AI to come up with a working solution.

I don't mean to respond to your 'professional work' scenario, but I find it quite useful to first let it draft a PLAN.md, even when "in many cases" it would one-shot some implementation without it. I mostly prompt it with a problem statement, "write a PLAN.md", "ask me any questions in prose and numbered", "don't start implementation until my say-so". The back-and-forth questions are often pretty significant to the final result, and I can (skim) review the plan and make other adjustments.

When you ask most models to write that plan, you see an extended thinking trace similar to implementation itself, but now all the decisions are made up front. If you one-shot it an implementation, those decisions are sprinkled all over the implementation phase, while half of it has been written and some architectural choices have already been locked in. I then frequently adjust that plan to end up (IMO) with a much better implementation, or much better suited to my situation, with less shortcuts.

It seems that the setup might be useful to record the moves of a mouse in order to place traps or locate its nest.

The problem was actually described in the agent output that I hadn't read when requested that additional feature:

> Distances only fix the layout up to translation, rotation and mirror image. That doesn't matter for the maths, but the map I'm shown has to match the real room, so the UI needs "rotate" and "flip" controls, or a way to say "Blue is next to the door".

https://github.com/simonw/beep-locator/blob/main/problem.md#...

Yes, but where would the fun in that be?

No, no. Instead of taking the time to unpack the boxes, it's better to spend time to play with AI, and leave the boxes unpacked forever.

The less obvious part is giving Claude five WebAudio ears spread around a room, wired together with WebSockets and using synchronized chirps to estimate each other's locations.

I spend $200/month on an Anthropic subscription which this all fit into easily, and I don't have a good estimate for the first part (in Claude Code Cloud with Opus 5.5), but the subsequent Fable 5.2 session on my laptop would have cost $31.04 at API prices (517.9k ctx / 331.4k out), according to `uvx agentsview serve`.

It makes me feel great!

There is no world in which I would have spent the days (more likely weeks) necessary to learn enough about audio analysis in both JavaScript and Python and the WebAudio APIs necessary to build this thing, just to help me identify an annoying beep.

Thanks to coding agents, I got to build a wildly ambitious system that still taught me a bunch of interesting things about audio analysis and network web application design, all in about an hour and a half of clock time.

The alternative wasn't learning those things at increased detail, it was not learning anything about them at all.

And I added more tools to my tool belt for the future. I now know that it's possible to measure distances to sounds using cheap devices over a network, and I've got code in a GitHub repository that shows exactly how to do that.

The trick where the server could inject additional JS modules into the clients without needing to refresh the page (and hence lose the microphone permission) was neat, too.

HTML and JavaScript. Here's the code that ran on each of the listeners: https://github.com/simonw/beep-locator/blob/main/beep_locato... and https://github.com/simonw/beep-locator/blob/main/beep_locato...

I'm not convinced the heading "Here's how I meticulously typed out and debugged code implementing an algorithm from a 2007 Microsoft Research paper" would have been any more interesting.

Did you really learn nothing at all from this?