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Comment by coldcode | Hacker News Reader

I'm sorry this is completely bogus, if there was ultrasonic audio emanating from everyone's phones dogs would go nuts. We can't hear it but they sure can.

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I disagree. I was recently in the transmitter room of a radio station and saw an interesting device. I asked the engineer what it was, he explained it was for ratings and worked exactly in the way the article describes. They transmit inaudible tones on the radio, and they are picked up by certain people with a device or the app installed. I don't recall all of the details but some googling will probably get you going.

They use this to determine how many people are listening to their station.

I wish I knew what those apps were. Or what signs I can look for. I generally don't have many "garbage" apps on my phone, but I've always suspected it with words with friends--Yes, my gf have been playing that game together since we started dating 5 years ago. Every so often an Ad will come on and the volume all of a sudden adjusts itself from mute to about 33%. Its distributing that an advertisement can have that power.

edit: Hey wait, let me read the article--just poured my first morning cup of coffee and reading HN.

I think it's an app specifically installed for the purpose. I just asked him what it was called, he said it was an Arbitron(now owned by Nielson) device. I googled Arbitron device and found this: https://en.m.wikipedia.org/wiki/Portable_People_Meter

Note that it doesn't use ultrasound, it embeds information in the normal audio in a way that humans are not likely to perceive (psychoacoustic masking).

Discussed ~1yr ago: https://news.ycombinator.com/item?id=10562207

Ultrasound doesn't mean the volume is really loud, just that it's at a higher frequency. If it's transmitting data then it's gibberish that adds to the background noise for an ultrasound listener. Maybe annoying but not necessarily driving one nuts.

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

Some food for thought.

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