I’m a bit perplexed by this story. Staff at Cuba’s embassy were sickened by this noise. I listened to the recording and I can’t imagine tolerating it for long.
Why didn’t the embassy immediately call in people with equipment to isolate it and find the source? State Dept could get help from many sources like the military or intelligence agencies. The article I quoted says the investigation is inconclusive.
I’ve worked in electronics most of my adult life. I’ve used frequency generators and owned an oscilloscope for many years. Any signal can be detected, recorded and studied. Whoever is doing this may have turned off their transmitter while the official team investigated. But you can give staff special recorders to carry and use when they hear the noise. A device could warn staff of noises just outside their range of hearing.
Early story on the sound and effects on embassy staff. Some people have hearing loss.
Recording of the sound. I wonder if white noise would counter it? I’d certainly wear earplugs if I had to work or live with that sound. The high pitch is very annoying. Probably coming from a sweep generator and then modified.
The Cubans are cooperating in the investigation. I don’t think they are behind it. They didn’t have to agree to renew diplomatic ties to the US a few years ago. Someone wants to drive a new wedge between the US and Cuba.
Perhaps the Russians, Putin? This is exactly the kind of weapon the old KGB loved.
Already there! I can only hear it with my right ear, and it’s only annoying. At a lower volume it could be blocked out by the earplugs I wear at night, anyway. However, if Prog Rock has taught us anything it’s to use your wheels; it is what they are for.
I could not hear a thing. I have moderate hearing loss at medium high frequencies and probably serious loss at high frequencies. I used to be able to hear the 15,750 Hz of a TV turned on anywhere in the house, but that has long since disappeared.
I agree it seems much likelier to be Russian than Cuban doing.
So YouTube’s audio is only designed to accommodate audio of a particular spectrum, and if someone posts, say, a recording of a bat using ultrasound, the YouTube “equipment” just acts as if it does not exist?
I agree this a very localized device. Hidden in the building or perhaps on a outside wall. It’s probably radio controlled. So it can be remotely activated and shut off.
Yes, audio amplifiers have filters to remove unneeded low and high frequencies. High frequencies often create an annoying hiss. Low frequencies create a Rumble sound. Turntables used to create that rumble.
The preamp stage in your phone filters and digitizes the audio before it reaches the circuit that records it.
Don’t think that’s specific to YouTube. As far as I know, all the compression algorithms for audio dump all the stuff that is beyond human hearing ranges.
It’s a necessity in digital audio recording to cut off anything higher than half the sample rate. If you do not, then you get a bunch of aliasing: lower pitches that aren’t actually there. This is based on the Nyquist-Shannon sampling theorem. To put it as simply as I can, digital audio is sampled in distinct chunks, and if the pitch is high enough, the air vibrates so fast that the each sample can’t detect all the vibrations. So it detects it as a lower pitch than it actually is.
That said, we do usually sample at over twice the audible range these days. This is to avoid degradation as you apply digital filters. But, once the audio is fixed, we downsample to only a bit more than human hearing: 48k sample rate, so 24khz audio. Keeping the higher stuff that we can’t hear is extremely expensive, as the amount of data needed for accurate representation increases exponentially the higher the pitch.
Then there’s audio compression. At a particular bitrate, you can cut off the high pitches that people can barely hear for a noticeable increase in quality in the pitches they can hear. YouTube’s audio quality varies based on the amount of bandwidth available, so it can actually even add more of a lowpass to increase perceived quality on the more important lower pitches.
Finally, there’s your equipment. Sound cards now are generally really cheap bits added to a motherboard, or even part of a system on a chip. They aren’t the highest quality. So they may not accurately reproduce higher pitches–so it’s makes sense to cut them off. And your speaker quality determines how accurate the higher pitches are. Speakers are tuned for the frequencies we can hear.
Point is, it’s not just that YouTube is cutting it off to save bandwidth. It’s a whole host of reasons why we stick to human audible frequencies in digital audio.
I say it’s a mass psychogenic illness. Someone got sick and heard a funny sound from a buzzing transformer or whatever, falsely associated the two and told everyone in the office, and suddenly dozens get the same symptoms. The symptoms are of course all the sort of vague thing one associates with fake illnesses.
So the volume has been doctored, both absolutely and relative to any other noises that might provide some kind of context. So it’s just, what, a pitch? Has the AP attempted to do something like make some control recordings in other office environments, to make sure that this supposed attack noise isn’t just normal electronic noise that seems out of place because of the effort to “increase volume and reduce background noise”?
Huh? I just opened your link to the Daily News article and listened to the audio clip which was prominently displayed at the top of the page. Then I continued reading the thread and saw this. Maybe they took it down and put it back?