I like the idea but I think it would be more useful it it was more reliable. Ignore all types of speed requirements and make it super reliable then it could actually be useful in special circumstances.

Receiving the audible sound did not work at all in any browser.

Receiving the ultrasonic (that is not very ultrasonic at all clearly hearable) did work in chrome and firefox.

Sometimes it figured out that there had been a message but not what it was. (saying missing packets)

Sending worked from all browsers.

When I lowered my mba volume to just two bars it still worked but I could no longer hear anything

audible text worked right away from iphone to my webcam. ultrasound had some packet loss , it had to be really close to the cam.

That's interesting. I experienced the opposite with my iPhone and AT2020 microphone. Ultrasonic always worked perfectly, audible complained of packet loss.

I am not sure what the noise floor looks like when comparing ultrasound to the normal audible range. It does seem unlikely to me that all this street noise would only be in the audible range and not ultrasonic, but since my ears can't hear ultrasound, I have no idea. Ultrasound did work better.

I tried the image as well; no idea if it worked. I got tired of waiting.

probably has to do with the webcam, mine was a microsoft HD cam

Tested sending text via ultrasonic from Chrome on a Mac to Chrome on an Android phone and it works as advertised (didn't test image tranmission).

Could this work as validation of geo positioning ? Instead of having to scan a specifically geo placed qr code (client side), having a web app that listen some encoded ultrasonic passphrase could match the feature

Edit : no safari support :(

I believe this is already used in retails stores, and passively listening app libraries are able to determine the user’s location.

I believe it is also used for television ads.

Do you know of any commercially available and reliable implementations of this sort of ultrasonic beacon that a startup could use?

I have a dream of a product I want to develop someday. I like to go to bars and do karaoke. But I would love to be able to open an app on my phone and submit the songs that I want to sing, then get an ETA for my next turn. To prevent abuse, the system should somehow validate that the user is in the venue. Having the user point their phone at a screen displaying a QR code would be problematic though, especially for people like me (I'm legally blind). Would an ultrasonic beacon work reliably, even in a noisy karaoke bar? Maybe a Bluetooth beacon or beacons would be better, but that would be more hardware for the venue or mobile karaoke DJ to buy and set up. Yes, I know, all of this is totally a first-world problem; I should focus on things that really matter.

I think this is a good idea. I agree with you about the QR code being problematic, simply because some bars are extremely crowded, and it would be difficult to ‘find’ the QR code.

Also, anybody could take a picture of the QR code and re-share it.

QR code gets a tad more secure if you couple with geolocation prompt.

Works!